# NAPCO Pump Company: Complete Technical Reference

> This file contains the full text content of napcopumps.com for AI assistants. See /llms.txt for the index version.

---

## Company Overview

NAPCO (North American Pump Company, L.L.C.) is a manufacturer of rotary gear pumps and factory-matched repair kits for industrial fluid transfer. Founded in 1995 and headquartered in Sandy, Utah (8744 Sandy Parkway, Unit E, Sandy, UT 84070), NAPCO serves industries worldwide including mining and explosives, chemical processing, petroleum and fuel transfer, adhesives and sealants, food and beverage, and general industrial applications.

NAPCO sells direct to end users and OEMs: no distributors, no middlemen. Contact: taylor@napcopumps.com | (801) 382-8881 | https://www.napcopumps.com

NAPCO pumps are precision-machined, hand-assembled, and tested before shipping. The company focuses exclusively on rotary gear pumps, not a broad product line, just a narrow one done exceptionally well. NAPCO operates across six continents and has supplied major mining, explosives, chemical, and industrial operations worldwide.

Sales model: Email-first workflow, payment-in-advance, customer-arranged freight. Lead times vary. Please contact us for current lead times.

---

## Products

### Rotary Gear Pumps

NAPCO manufactures external rotary gear pumps in 2-inch and 3-inch port sizes, available in ductile iron or stainless steel. All pumps are self-priming, bi-directional, and fully field-serviceable without returning the pump to the factory.

Model naming convention:
- PA = Pump Assembly
- 200 = 2-inch port / 300 = 3-inch port
- C = Ductile Iron / S = Stainless Steel

---

#### PA300S: 3-Inch Stainless Steel Rotary Gear Pump

URL: https://www.napcopumps.com/products/pa300s

Specifications:
- Port Size: 3-inch NPT
- Housing Material: Stainless Steel
- Shaft Material: Stainless Steel
- Gear Options: Nitrile rubber (standard, rated to 240°F) or Viton
- Seals: Viton high-pressure and low-pressure seals
- Bearings: Roller type
- Max Flow Rate: 158 GPM at 280 RPM
- Max Operating Pressure: 100 PSI (tested)
- Weight: 173 lbs net
- Shipping carton: 13 x 19 x 16 inches
- Rotation: Bi-directional (CW or CCW)
- Priming: Self-priming

Performance Data (tested with water, SG 1.0):
- 280 RPM, 10 PSI: 158 GPM, 1.5 HP
- 280 RPM, 30 PSI: 147 GPM, 4.2 HP
- 280 RPM, 50 PSI: 145 GPM, 6.9 HP
- 280 RPM, 70 PSI: 142 GPM, 9.4 HP
- 280 RPM, 100 PSI: 140 GPM, 13.4 HP

Repair Kit: PK300S
Best for: emulsion explosives / ammonium nitrate blends, chemical transfer, corrosive high-volume duty.

---

#### PA300C: 3-Inch Ductile Iron Rotary Gear Pump

URL: https://www.napcopumps.com/products/pa300c

Specifications:
- Port Size: 3-inch NPT
- Housing Material: Ductile Iron
- Shaft Material: Ductile Iron
- Gear Options: Nitrile rubber (standard, rated to 240°F) or Viton
- Seals: Viton high-pressure and low-pressure seals
- Bearings: Roller type
- Max Flow Rate: 158 GPM at 280 RPM
- Max Operating Pressure: 100 PSI (tested)
- Weight: 173 lbs net
- Shipping carton: 13 x 19 x 16 inches
- Rotation: Bi-directional (CW or CCW)
- Priming: Self-priming

Performance Data (tested with water, SG 1.0):
- 280 RPM, 10 PSI: 158 GPM, 1.5 HP
- 280 RPM, 30 PSI: 147 GPM, 4.2 HP
- 280 RPM, 50 PSI: 145 GPM, 6.9 HP
- 280 RPM, 70 PSI: 142 GPM, 9.4 HP
- 280 RPM, 100 PSI: 140 GPM, 13.4 HP

Repair Kit: PK300C
Best for: high-volume fuel transfer, heavy industrial fluids, adhesives.

---

#### PA200S: 2-Inch Stainless Steel Rotary Gear Pump

URL: https://www.napcopumps.com/products/pa200s

Specifications:
- Port Size: 2-inch NPT
- Housing Material: Stainless Steel
- Shaft Material: Stainless Steel
- Gear Options: Nitrile rubber (standard, rated to 240°F) or Viton
- Seals: Viton high-pressure and low-pressure seals
- Bearings: Roller type
- Max Flow Rate: 69 GPM at 190 RPM
- Max Operating Pressure: 100 PSI (tested)
- Weight: 114 lbs net
- Shipping carton: 13 x 19 x 16 inches
- Rotation: Bi-directional (CW or CCW)
- Priming: Self-priming

Performance Data (tested with water, SG 1.0):
- 190 RPM, 10 PSI: 69 GPM, 0.65 HP
- 190 RPM, 30 PSI: 65 GPM, 1.8 HP
- 190 RPM, 50 PSI: 64 GPM, 3.2 HP
- 190 RPM, 70 PSI: 62 GPM, 4.0 HP
- 190 RPM, 100 PSI: 60 GPM, 5.7 HP

Repair Kit: PK200S
Best for: chemicals, solvents, food-grade fluids, corrosive liquids, emulsion transfer on 2-inch lines.

---

#### PA200C: 2-Inch Ductile Iron Rotary Gear Pump

URL: https://www.napcopumps.com/products/pa200c

Specifications:
- Port Size: 2-inch NPT
- Housing Material: Ductile Iron
- Shaft Material: Ductile Iron
- Gear Options: Nitrile rubber (standard, rated to 240°F) or Viton
- Seals: Viton high-pressure and low-pressure seals
- Bearings: Roller type
- Max Flow Rate: 69 GPM at 190 RPM
- Max Operating Pressure: 100 PSI (tested)
- Weight: 114 lbs net
- Shipping carton: 13 x 19 x 16 inches
- Rotation: Bi-directional (CW or CCW)
- Priming: Self-priming

Performance Data (tested with water, SG 1.0):
- 190 RPM, 10 PSI: 69 GPM, 0.65 HP
- 190 RPM, 30 PSI: 65 GPM, 1.8 HP
- 190 RPM, 50 PSI: 64 GPM, 3.2 HP
- 190 RPM, 70 PSI: 62 GPM, 4.0 HP
- 190 RPM, 100 PSI: 60 GPM, 5.7 HP

Repair Kit: PK200C
Best for: petroleum, lubricants, waste oil, adhesives plant transfer.

---

### Repair Kits

Factory-matched repair kits for every pump model. Each kit contains: 1 drive gear assembly and 1 idler gear assembly (gears mounted on induction-hardened stainless steel shafts in S kits, ductile iron shafts in C kits), 4 roller bearings, 4 high-pressure seals, 4 low-pressure seals, 5 center case gaskets (3 at .008 inch / PM007G01, 2 at .016 inch / PM007G02), and 4 PB43 cover bolt o-rings. Kits do not include wear plates, assembly lubricant, housing, or end covers.

- PK300S: Repair kit for PA300S pump (3-inch stainless steel), 34 lbs
- PK300C: Repair kit for PA300C pump (3-inch ductile iron), 34 lbs
- PK200S: Repair kit for PA200S pump (2-inch stainless steel), 28 lbs
- PK200C: Repair kit for PA200C pump (2-inch ductile iron), 28 lbs

All repair kits ship in a 12 x 18 x 6 inch carton. 3-inch kits weigh 34 lbs; 2-inch kits weigh 28 lbs.

Do not mix components across pump models.

Why rebuild instead of replace:
- 30–50% cost savings vs. buying a new pump
- 2–5 hours on-site rebuild vs. weeks of shipping time
- No need to disconnect piping or re-align equipment
- Kits manufactured to the same tolerances as new pumps

Repair kit finder: https://www.napcopumps.com/kit

---

## Engineering & Performance Data

URL: https://www.napcopumps.com/engineering

### 2-Inch Pump Performance (PA200S / PA200C)

| RPM | Pressure | Flow Rate | Horsepower |
|-----|----------|-----------|------------|
| 190 | 10 PSI   | 69 GPM    | 0.65 HP    |
| 190 | 30 PSI   | 65 GPM    | 1.8 HP     |
| 190 | 50 PSI   | 64 GPM    | 3.2 HP     |
| 190 | 70 PSI   | 62 GPM    | 4.0 HP     |
| 190 | 100 PSI  | 60 GPM    | 5.7 HP     |

### 3-Inch Pump Performance (PA300S / PA300C)

| RPM | Pressure | Flow Rate | Horsepower |
|-----|----------|-----------|------------|
| 280 | 10 PSI   | 158 GPM   | 1.5 HP     |
| 280 | 30 PSI   | 147 GPM   | 4.2 HP     |
| 280 | 50 PSI   | 145 GPM   | 6.9 HP     |
| 280 | 70 PSI   | 142 GPM   | 9.4 HP     |
| 280 | 100 PSI  | 140 GPM   | 13.4 HP    |

### Pump Materials & Composition

Ductile Iron models (PA300C / PA200C):
- Shaft: Ductile Iron
- Gears: Nitrile Rubber (standard)
- Housing: Ductile Iron
- Gaskets: Asbestos-Free Paper
- High-Pressure Seal: Viton
- Low-Pressure Seal: Viton
- Bearings: Roller

Stainless Steel models (PA300S / PA200S):
- Shaft: Stainless Steel
- Gears: Nitrile Rubber (standard)
- Housing: Stainless Steel
- Gaskets: Asbestos-Free Paper
- High-Pressure Seal: Viton
- Low-Pressure Seal: Viton
- Bearings: Roller

### Pump Dimensional Data (inches)

Taken from the NAPCO factory drawings NAP200 and NAP300 (Sept 2019). One drawing
set per port size; the stainless and ductile iron versions of a size share it.
Only dimensions the factory sheets state are listed: nothing is interpolated.

3-inch (PA300S / PA300C):
- Overall length: 11.50
- Overall height: 12.97 (8.34 top to shaft centreline + 4.63 shaft centreline to base)
- Case width: 8.38
- Across port flanges: 10.75
- Port centrelines: 6.75 and 2.12
- Shaft protrusion: 3.62
- Shaft end thread: 5/8-11 tpi
- Port connection: 3-inch 150# ANSI threaded (NPT) flange
- Foot: 5.970 +/-.005 x 3.63, hole offsets 2.19 and 1.19
- Mounting holes: 4 x 0.690 diameter thru floor

2-inch (PA200S / PA200C):
- Overall length: 11.50
- Overall height: 12.75
- Overall width at base: 6.30
- Cover bolt pattern: 4.91
- Shaft centrelines: 8.75 and 4.50 above base (drive shaft may be fitted in either position)
- Shaft protrusion: 4.75
- Shaft diameter: 1.125, keyway 0.25 x 3.52
- Port connection: 2-inch NPT typical
- Foot: 10.50 long x 4.25 wide, shaft offset 2.13
- Mounting holes: 2 x 0.64 diameter

### Relief Valve Requirement

A mechanical relief valve or external bypass is mandatory on all NAPCO rotary gear pumps. The relief valve should be set below the pump's maximum rated differential pressure. Rotary gear pumps are positive displacement: they will build pressure until something fails if no relief path exists.

---

## Rotary Gear Pump

URL: https://www.napcopumps.com/resources/rotary-gear-pump-working-principle

A rotary gear pump is a positive displacement pump that uses two meshing gears to transfer fluid. As the gears unmesh on the inlet side, they create an expanding cavity that draws fluid in. Fluid is carried between the gear teeth and the pump housing around the outside of each gear. As the gears mesh again on the discharge side, the cavity contracts and forces fluid out under pressure.

### Key Operating Characteristics

- Positive displacement: Flow rate is proportional to shaft speed; double the RPM, double the flow
- Self-priming: The gear mechanism creates sufficient vacuum to lift fluid from a reservoir
- Bi-directional: Reversing drive rotation reverses flow direction; no re-plumbing required
- Viscosity-tolerant: flow is near-constant regardless of viscosity or pressure

### Types of Gear Pumps

External gear pumps (NAPCO design): Two identical gears on parallel shafts. Simple, rugged, field-serviceable. Best for industrial transfer applications.

Internal gear pumps: Larger outer gear and smaller inner gear with a crescent divider. Smoother flow, but more complex to service. Common in hydraulic systems.

### Key Components

| Component | Function |
|-----------|----------|
| Housing/Body | Contains pressure, provides fluid path |
| Drive Gear | Powered by motor shaft, drives idler gear |
| Idler Gear | Meshes with drive gear to complete the pumping action |
| Shaft | Transfers torque from motor to drive gear |
| Bearings | Support shaft, minimize friction and wear |
| Seals | Prevent fluid from leaking along shaft |
| Gaskets | Seal between housing components |

### Rotary Gear Pumps vs. Other Pump Types

| Factor | Rotary Gear Pump | Centrifugal Pump | Progressive Cavity Pump |
|--------|-----------------|-----------------|------------------------|
| Pump type | Positive displacement | Dynamic | Positive displacement |
| Self-priming | Yes | Limited | Limited |
| Viscosity handling | Excellent | Poor (loses head with thick fluids) | Excellent |
| Bi-directional | Yes | No | No |
| Field serviceability | Excellent (drop-in repair kit) | Moderate | Complex |
| Best for | Viscous fluid transfer | High-flow, low-viscosity | High-pressure metering |

### Common Applications

- Explosives & Mining: Emulsion explosives, ANFO, bulk slurry
- Adhesives & Sealants: Epoxies, resins, structural adhesives
- Chemical Processing: Acids, solvents, caustics, polymers
- Petroleum & Fuel: Diesel, fuel oil, crude oil, lubricants, waste oil
- Food & Beverage: Syrups, edible oils, chocolate, flavorings
- General Industrial: Paints, coatings, inks, asphalt

---

## How to Size a Rotary Gear Pump

URL: https://www.napcopumps.com/resources/how-to-size-rotary-gear-pump

### Step 1: Determine Required Flow Rate (GPM)

Calculate baseline flow rate: Total volume needed ÷ available time = required GPM
Add 15–20% safety margin to account for viscosity variation, wear over time, and system inefficiencies.

Gear pump flow rate formula:
Flow (GPM) = Displacement (GPM/RPM) × RPM × Volumetric Efficiency

NAPCO reference:
- PA300 series: larger displacement, up to 158 GPM at 280 RPM
- PA200 series: smaller displacement, up to 69 GPM at 190 RPM

### Step 2: Determine System Pressure

Add all pressure sources:
- Back pressure from downstream equipment (filters, valves, meters)
- Hydrostatic head: 0.433 PSI per vertical foot of discharge elevation
- Line friction loss: approximately 2–5 PSI per 100 feet of pipe at typical flow rates

Always size at MAXIMUM expected system pressure.

Performance at pressure reference:

| Model  | 10 PSI  | 50 PSI  | 70 PSI  | 100 PSI |
|--------|---------|---------|---------|---------|
| PA300S | 158 GPM | 145 GPM | 142 GPM | 140 GPM |
| PA200S | 69 GPM  | 64 GPM  | 62 GPM  | 60 GPM  |

### Step 3: Consider Fluid Viscosity

Viscosity impact on gear pump performance:
- Thicker fluids improve sealing (internal slip decreases), so volumetric efficiency rises with viscosity
- Thinner fluids (water, gasoline) slip more internally, so volumetric efficiency is lower

Typical viscosity ranges:
- Light petroleum products: 32–100 cSt
- Water-based adhesives: 50–1000 cSt
- High-viscosity adhesives: 1000–5000 cSt

### Step 4: Choose Pump Body Material

Ductile Iron (C suffix, PA300C, PA200C):
- Best for non-corrosive fluids
- Petroleum products, adhesives, paints, lubricants
- Lower initial cost
- Ductile iron shaft

Stainless Steel (S suffix, PA300S, PA200S):
- Best for corrosive fluids (acids, solvents, ammonium nitrate solutions)
- Food-grade applications
- Higher initial cost than ductile iron
- Stainless steel shaft (prevents shaft pitting that leads to seal leakage)

### Step 5: Select Gear Material (Elastomer)

Nitrile Rubber (NBR, standard):
- Temperature rating: 240°F
- Compatible with: Petroleum products, emulsions, water-based fluids, moderate chemicals, adhesives
- Not compatible with: Aromatic solvents, chlorinated solvents, strong oxidizers

Viton (FKM, optional upgrade):
- Temperature range: extends above nitrile's 240°F rating
- Compatible with: Aromatic solvents, chlorinated solvents, strong acids, oxidizers, petroleum
- Higher cost than nitrile

### NAPCO Pump Sizing Reference

| Model  | Port | Housing       | Displacement | Max RPM | Flow @ 10 PSI | Flow @ 100 PSI | Max Pressure |
|--------|------|---------------|-------------|---------|---------------|----------------|-------------|
| PA300S | 3"   | Stainless     | ~0.56 GPM/RPM | 280   | 158 GPM       | 140 GPM        | 100 PSI     |
| PA300C | 3"   | Ductile Iron  | ~0.56 GPM/RPM | 280   | 158 GPM       | 140 GPM        | 100 PSI     |
| PA200S | 2"   | Stainless     | ~0.36 GPM/RPM | 190   | 69 GPM        | 60 GPM         | 100 PSI     |
| PA200C | 2"   | Ductile Iron  | ~0.36 GPM/RPM | 190   | 69 GPM        | 60 GPM         | 100 PSI     |

### Practical Sizing Examples

Example 1: Explosives (emulsion transfer):
- Need: 80 GPM, 30 PSI, ammonium nitrate emulsion
- Emulsion corrodes ductile iron → stainless steel required
- PA300S at 280 RPM delivers 147 GPM at 30 PSI → throttle down to 80 GPM via speed control

Example 2 (adhesive transfer):
- Need: 40 GPM, 50 PSI, adhesive (~2000 cSt)
- Non-corrosive → ductile iron acceptable
- PA200C at 190 RPM delivers 64 GPM at 50 PSI → use variable speed drive to achieve 40 GPM

Example 3 (chemical processing):
- Need: 30 GPM, 75 PSI, solvent with aromatic content
- Corrosive + aromatic → stainless steel + Viton gears
- PA200S with Viton gears at reduced speed

### Common Sizing Mistakes

1. Sizing at nominal pressure, not maximum: always use worst-case system pressure
2. Ignoring pressure derate: flow drops 5–15% from 10 PSI to 100 PSI
3. No safety margin: add 15–20% to account for wear and viscosity variation
4. Wrong elastomer: aromatic solvents with nitrile gears causes rapid swelling and failure
5. Exceeding max RPM: wear increases dramatically above rated speed

---

## Nitrile vs. Viton Gear Selection Guide

URL: https://www.napcopumps.com/resources/nitrile-vs-viton-gears

### Nitrile Rubber (NBR) Gears (Standard)

Physical properties:
- Temperature rating: 240°F
- Excellent rebound and resilience
- Outstanding tear resistance
- Economical, standard option on all NAPCO pumps

Chemical compatibility:
- Compatible: Petroleum products, mineral oils, hydraulic fluids, water-based emulsions, moderate chemical exposure, most adhesives
- Incompatible: Aromatic solvents (rapid swelling), chlorinated solvents, strong oxidizers, ozone degradation, temperatures above 240°F

### Viton (FKM) Gears (Optional Upgrade)

Physical properties:
- Temperature range: extends above nitrile's 240°F rating
- Superior chemical resistance, minimal fluid swell
- Excellent ozone and UV resistance
- Slightly lower rebound than nitrile
- Higher cost than nitrile

Chemical compatibility:
- Compatible: Aromatic solvents (toluene, xylene, benzene), chlorinated solvents, strong acids, oxidizers, petroleum products, high-temperature fluids
- Incompatible: Low-molecular-weight esters and ketones, water/steam at high temperatures

### Detailed Comparison

| Property               | Nitrile (NBR)           | Viton (FKM)             |
|------------------------|------------------------|------------------------|
| Temperature max        | 240°F                  | Above 240°F            |
| Petroleum resistance   | Excellent              | Excellent              |
| Aromatic solvent       | Poor (swells)          | Excellent              |
| Chlorinated solvent    | Poor                   | Excellent              |
| Strong acid resistance | Moderate               | Good to Excellent      |
| Water resistance       | Good                   | Good                   |
| Tear resistance        | Excellent              | Good                   |
| Rebound/resilience     | Excellent              | Good                   |
| Cost                   | Standard               | Higher                 |
| Best for               | Petroleum, emulsions   | Solvents, chemicals    |

### Application-Based Selection Guide

| Application                     | Recommendation              | Rationale                                     |
|---------------------------------|-----------------------------|-----------------------------------------------|
| Emulsion explosives             | Nitrile (standard)          | Water-based, non-aromatic, economical         |
| Solvent-based adhesives         | Viton (recommended)         | Aromatic content causes nitrile swelling      |
| Water-based adhesives           | Nitrile (preferred)         | Non-aromatic, cost-effective                  |
| Fuel & petroleum transfer       | Nitrile (standard)          | Proven compatibility, cost-effective          |
| Aggressive chemicals/solvents   | Viton (required)            | Nitrile will fail rapidly                     |
| High-temperature service (>240°F) | Viton (required)          | Nitrile hardens and fails at high temps       |
| Food-grade applications         | Nitrile or Viton            | Depends on fluid chemistry                    |

### Quick Decision Guide

Use Viton if:
- Fluid contains aromatic solvents (toluene, xylene, benzene, MEK)
- Fluid contains chlorinated hydrocarbons
- Operating temperature exceeds 240°F continuously
- Extended service intervals justify the cost premium

Use Nitrile if:
- Fluid is petroleum-based (diesel, fuel oil, crude, lubricants)
- Fluid is water-based (emulsions, adhesives, aqueous solutions)
- Temperature stays below 240°F
- Cost is a primary consideration

---

## Stainless Steel vs. Ductile Iron Pump Selection

URL: https://www.napcopumps.com/resources/stainless-steel-vs-ductile-iron-pumps

### Why Housing Material Matters

The pump housing is the first line of defense against the fluid being pumped. Wrong material selection leads to corrosion, contamination, seal failure, and pump failure. Housing material also determines shaft material: stainless pumps get stainless shafts, ductile iron pumps get ductile iron shafts. Shaft material matters because microscopic pitting on a corroded shaft leads to seal leakage.

### Stainless Steel Pumps (PA300S / PA200S)

Construction: stainless steel housing, stainless steel shaft, same bearings and seals as ductile iron.

Advantages:
- Superior corrosion resistance to acids, solvents, oxidizers, and chloride-containing fluids
- Required for ammonium nitrate-based emulsions (corrodes ductile iron)
- Required for food-grade applications
- Stainless shaft prevents microscopic pitting that leads to seal leakage

Best for: Emulsion explosives, chemical processing, food & beverage, pharmaceutical-adjacent, any chloride-containing fluid.

### Ductile Iron Pumps (PA300C / PA200C)

Construction: Ductile iron housing, ductile iron shaft, same bearings and seals as stainless.

Advantages:
- Cost-effective, lower initial purchase price
- Rugged and forgiving in non-corrosive service
- Excellent strength and wear resistance
- Proven reliability in continuous-duty adhesive transfer and petroleum service
- Ductile iron shaft provides good strength in non-corrosive applications

Best for: Petroleum and fuel transfer, adhesives and sealants, paints and coatings, lubricants, waste oil, non-corrosive industrial fluids.

### Comparison Table

| Property               | Stainless Steel (PA-S)      | Ductile Iron (PA-C)          |
|------------------------|-----------------------------|------------------------------|
| Corrosion resistance   | Excellent (stainless)          | Moderate                     |
| Chemical compatibility | Broad: acids, bases, oxidizers | Non-corrosive fluids only |
| Weight                 | Similar                     | Similar                      |
| Tensile strength       | ~80,000 PSI                 | ~70,000 PSI                  |
| Service life (corrosive) | Excellent               | Poor: will corrode          |
| Service life (non-corrosive) | Excellent            | Excellent                    |
| Flow/pressure rating   | Identical within size class | Identical within size class  |
| Shaft material         | Stainless Steel             | Ductile Iron                 |

### Industry-Specific Recommendations

| Industry                    | Recommended Model       | Reason                                              |
|-----------------------------|------------------------|-----------------------------------------------------|
| Explosives & Mining         | PA300S or PA200S       | Ammonium nitrate corrodes ductile iron               |
| Adhesives & Sealants        | PA300C or PA200C       | Non-corrosive fluids, ductile iron cost-effective   |
| Chemical Processing         | PA300S or PA200S       | Acids, bases, oxidizers attack iron                  |
| Petroleum & Fuel Transfer   | PA300C or PA200C       | Non-corrosive petroleum, proven performance         |
| Food & Beverage             | PA300S or PA200S       | Food-grade stainless steel required                  |
| General Industrial          | PA300C or PA200C       | Most industrial fluids are non-corrosive             |

Note: Within the same port size, stainless and ductile iron models have identical flow rates, pressures, and displacements. The only differences are housing material, shaft material, and price.

---

## Gear Pumps vs. Progressive Cavity Pumps

URL: https://www.napcopumps.com/resources/gear-pumps-vs-progressive-cavity-pumps

Both are positive displacement pumps: they move a fixed volume per revolution, so flow is near-constant regardless of viscosity or pressure. The difference is in mechanism and optimal application range.

### How Gear Pumps Work

Two meshing gears create expanding and contracting cavities. Simple direct mechanical action. Self-priming by design. Bi-directional by reversing shaft rotation. Field-serviceable with drop-in repair kits.

### How Progressive Cavity Pumps Work

A helical rotor turns inside a double-helix elastomeric stator. The geometry creates sealed cavities that move progressively from suction to discharge. Smooth, nearly pulsation-free flow. Better for high-pressure downhole pumping and metering extremely viscous fluids.

### Detailed Comparison

| Factor                  | Rotary Gear Pump         | Progressive Cavity Pump       |
|-------------------------|--------------------------|-------------------------------|
| Moving parts            | Two gears, simple       | Rotor + stator, complex geometry |
| Field rebuild           | Drop-in kit, no alignment | Stator replacement, rotor alignment |
| Self-priming            | Yes, inherent design    | Limited, requires flooded suction |
| Bi-directional          | Yes, reverse rotation   | No, single direction only    |
| Pulsation               | Slight (2 gears)         | Very low (near pulsation-free) |
| Max pressure            | 100 PSI tested           | 500+ PSI achievable           |
| Viscosity handling      | Wide range               | 10,000+ cSt                   |
| Capital cost            | Lower                    | Higher                        |
| Maintenance cost        | Lower (field rebuild)    | Higher (stator replacements)  |

### When to Choose a Gear Pump

- System pressure below 100 PSI
- Loading and unloading operations requiring bi-directional flow
- Remote locations where field serviceability is critical
- Cost-sensitive applications
- Viscous fluid transfer
- Need to handle air or prime from empty

### When to Choose a Progressive Cavity Pump

- High pressure required (150+ PSI, especially downhole pumping)
- Extremely high viscosity fluids (5000+ cSt)
- Precision metering with near-zero pulsation required
- Extended suction lift requirements
- Single direction of flow only

### Application Focus: Explosives Industry

Zero-pressure emulsion transfer at surface (loading):
Gear pumps are ideal. Bi-directional loading and unloading without re-plumbing, consistent low-pressure delivery, self-priming for truck/tank transfers, simple pressure adjustment.

Downhole pumping (blast hole loading):
Progressive cavity pumps excel. Maintain stable flow at 500+ PSI down a blast hole, excellent handling of high-viscosity sensitized emulsion, low sensitivity to variations in suction head.

Both pump types are used in emulsion explosives operations: gear pumps for surface transfer, PCPs for deep-hole loading.

---

## Industries Served

### Explosives & Mining

URL: https://www.napcopumps.com/industries/explosives-mining

NAPCO rotary gear pumps handle emulsion explosives, ANFO solutions, bulk slurry transfer, and matrix manufacturing. The PA300S and PA200S (stainless steel) are standard in this industry: ammonium nitrate-based emulsions are corrosive to ductile iron.

Key advantages for explosives:
- Self-priming: No external priming needed for truck-to-tank and tank-to-hole transfers
- Bi-directional: Reverse rotation for loading and unloading without re-plumbing the system
- Field-serviceable: Complete rebuild with factory-matched repair kits in 2–5 hours on-site
- Consistent flow: Positive displacement delivers predictable flow regardless of emulsion viscosity

Recommended pumps:
- PA300S: 3-inch stainless, 158 GPM at 280 RPM, 100 PSI max
- PA200S: 2-inch stainless, 69 GPM at 190 RPM, 100 PSI max

Typical applications: Bulk emulsion transfer, ammonium nitrate emulsion pumping, matrix manufacturing, mine site pump-over systems.

---

### Explosives & Mining: Application Guide (Deep Reference)

Source: https://www.napcopumps.com/resources/rotary-pumps-explosives-mining

Why gear pumps for emulsion explosives:
- Emulsion explosives are suspensions of fuel oil, ammonium nitrate, water, and sensitizers. Turbulence destabilizes the suspension (emulsifier breakdown, oil separation, foam). Gear pumps move emulsion with laminar, low-shear flow: centrifugal pumps are unsuitable.
- Positive displacement: flow is near-constant regardless of viscosity or pressure, unlike a centrifugal pump.
- Bi-directional operation enables loading/unloading and reverse-flow cleanup without re-plumbing.
- Self-priming for truck-to-tank and tank-to-hole transfers.

Material selection (critical):
- Stainless steel (PA300S, PA200S) is the industry standard for emulsion explosives, ammonium nitrate-based emulsions are corrosive to ductile iron. Stainless steel also resists salt spray, mining runoff, and acidic groundwater.
- Ductile iron (PA300C, PA200C) is appropriate for non-corrosive mining support fluids: fuel oil, diesel, lubricants, waste oil. Never use ductile iron in direct ammonium nitrate emulsion service.
- Nitrile gears are standard for emulsions (water-based, non-aromatic). Viton for aromatic solvents or temperatures above 240°F.

Pump sizing for explosives duty:
- PA300S: 158 GPM at 280 RPM / 10 PSI, 140 GPM at 100 PSI. Bulk plant transfer, truck loading, high-throughput matrix transfer.
- PA200S: 69 GPM at 190 RPM / 10 PSI, 60 GPM at 100 PSI. Portable loading units, small batch, skid-mounted field systems.
- Typical ANFO/emulsion loading trucks run 30–80 GPM. Set relief valves 10–20% above max operating pressure but within the pump's rated limit.
- Maximum tested operating pressure: 100 PSI (all models).

ANFO clarification (common question):
- Straight ANFO (ammonium nitrate prills + ~6% fuel oil) is a dry granular blasting agent; it is augered or pneumatically loaded, NOT pumped.
- Pumpable AN products: emulsion explosive matrix, ammonium nitrate solution, and heavy ANFO blends with high emulsion content.
- Full guide: https://www.napcopumps.com/resources/ammonium-nitrate-anfo-pumping
- Cartridge emulsion explosives (packaged product is hand-loaded; stainless gear pumps move bulk matrix): https://www.napcopumps.com/resources/cartridge-emulsion-explosives
- ANFO vs emulsion (dry prill vs pumpable matrix; stainless PA300S / PA200S for bulk matrix only): https://www.napcopumps.com/resources/anfo-vs-emulsion

Surface transfer vs. downhole loading:
- Gear pumps: surface transfer, truck loading, matrix manufacturing, pump-over systems.
- Progressive cavity pumps: deep blast-hole loading at 500+ PSI. Both technologies coexist in emulsion operations.

Field serviceability at remote mine sites:
- Complete rebuild in 2–5 hours on-site with factory-matched repair kits (PK300S/PK200S for stainless). No factory return.
- Stock repair kits at the mine site; quarterly seal inspection, inlet strainer cleaning (150-micron), annual bulk tank flush.
- High- and low-pressure Viton seals are included in every repair kit.

System design best practices:
- 150-micron inlet strainer minimum; 75–100 micron for high-use operations.
- Discharge velocity under 8 ft/sec (2-inch line typical for PA300S at 158 GPM).
- Stainless discharge piping and fittings for outdoor/coastal mining environments.

---

### Adhesives & Sealants

URL: https://www.napcopumps.com/industries/adhesives-sealants

NAPCO ductile iron pumps are the proven choice for high-viscosity adhesive and sealant transfer. PA300C is the most popular model in wood products manufacturing and packaging adhesive applications.

Key advantages:
- High-viscosity capable: Handles epoxies, structural adhesives, and resins
- Self-priming: Draws from drums, totes, and bulk tanks
- Bi-directional: Return fluid to reservoir by reversing rotation
- Consistent output: flow is near-constant regardless of viscosity or pressure

Recommended pumps:
- PA300C: 3-inch ductile iron, 158 GPM at 280 RPM (most popular)
- PA200C: 2-inch ductile iron, 69 GPM at 190 RPM

Typical applications: Wood products manufacturing, construction sealants, epoxy and resin systems, packaging adhesives.

Plant transfer spec (PA300C/PA200C, S models if formula attacks iron): https://www.napcopumps.com/resources/adhesive-pump

---

### Chemical Processing

URL: https://www.napcopumps.com/industries/chemical-processing

NAPCO stainless steel pumps with Viton gears handle acids, solvents, caustics, and corrosive process chemicals.

Key advantages:
- Corrosion resistant: stainless steel housing and shaft
- Chemical-compatible gears: Nitrile for standard chemicals, Viton for aggressive chemistry
- Seals: Viton high-pressure and low-pressure seals standard

Gear material selection for chemicals:
- Nitrile (standard): Up to 240°F, water-based solutions, moderate chemical exposure
- Viton (recommended for): Aromatic solvents, chlorinated hydrocarbons, strong acids and oxidizers, temperatures above 240°F

Recommended pumps:
- PA300S: 3-inch stainless, 158 GPM at 280 RPM
- PA200S: 2-inch stainless, 69 GPM at 190 RPM

Typical applications: Corrosive chemical transfer, solvent handling, polymer and resin processing, chemical batching, waste chemical handling.

Chemical resistant spec (stainless PA300S/PA200S, nitrile or Viton gears): https://www.napcopumps.com/resources/chemical-resistant-gear-pump

---

### Petroleum & Fuel Transfer

URL: https://www.napcopumps.com/industries/petroleum-fuel

NAPCO ductile iron pumps are proven workhorses for diesel, fuel oil, crude oil, lubricants, and waste oil. Petroleum products are non-corrosive: ductile iron is the cost-effective choice.

Recommended pumps:
- PA300C: 3-inch ductile iron, 158 GPM at 280 RPM, 100 PSI max
- PA200C: 2-inch ductile iron, 69 GPM at 190 RPM, 100 PSI max

Typical applications: Bulk fuel terminal transfer, tanker truck loading/unloading, diesel distribution, crude oil handling, lubricant packaging, waste oil collection, refinery process transfer.

---

### Food & Beverage

URL: https://www.napcopumps.com/industries/food-beverage

NAPCO stainless steel pumps handle syrups, edible oils, flavorings, chocolate, and other food-grade viscous fluids.

Key advantages:
- Stainless construction: Food-compatible material
- Gentle product handling: Positive displacement with no impeller violence
- Self-priming: Works with bulk tanks and drums
- Bi-directional: Return product to storage by reversing flow

Gear temperature ratings:
- Standard nitrile gears: Rated to 240°F
- Viton gears available: For hot chocolate, warm syrups, heated oil transfer above 240°F

Recommended pumps:
- PA300S: 3-inch stainless, 158 GPM at 280 RPM
- PA200S: 2-inch stainless, 69 GPM at 190 RPM

Typical applications: Syrups and sweeteners, edible oils and fats, chocolate and confectionery, flavorings and extracts, sauces and condiments.

Food grade gear pump (stainless PA200S and PA300S for plant transfer of food and beverage fluids): https://www.napcopumps.com/resources/food-grade-gear-pump

---

### General Industrial

URL: https://www.napcopumps.com/industries/general-industrial

NAPCO industrial gear pumps for plant transfer of paints, coatings, resins, lubricants, waste oil, and other demanding industrial fluids. Ductile iron or stainless. 2-inch and 3-inch ports. Made in Sandy, Utah.

Material selection for general industrial:
- Ductile Iron (PA300C / PA200C): Non-corrosive fluids: paints, coatings, inks, lubricants, petroleum, waste oil
- Stainless Steel (PA300S / PA200S): Corrosive solvents, chemically aggressive fluids, and cases where the housing must resist chemical attack

Complete pump lineup:
- PA300C, 3-inch ductile iron, 158 GPM at 280 RPM, 100 PSI max, 173 lbs
- PA300S, 3-inch stainless steel, 158 GPM at 280 RPM, 100 PSI max, 173 lbs
- PA200C, 2-inch ductile iron, 69 GPM at 190 RPM, 100 PSI max, 114 lbs
- PA200S, 2-inch stainless steel, 69 GPM at 190 RPM, 100 PSI max, 114 lbs

Typical applications: Paints and coatings, inks and dyes, lubricants and oils, waste oil and recycling, resins and polymers, asphalt and bitumen.

Paint and coating plant transfer (tank, tote, drum, truck load-out): https://www.napcopumps.com/resources/gear-pump-for-paint-transfer

---

## Maintenance & Service

### Rotary Gear Pump Maintenance Schedule

URL: https://www.napcopumps.com/resources/rotary-gear-pump-maintenance-schedule

#### Daily Checks (Every Shift)
- Visual leak inspection at all fittings, seals, and gasket faces
- Listen for unusual noise (cavitation, bearing rumble, gear contact)
- Check inlet and outlet pressure gauges against baseline
- Monitor motor amperage for increases indicating wear
- Verify consistent flow rate

#### Weekly Maintenance (~40 Operating Hours)
- Inspect and clean suction strainer
- Check for vibration at pump and motor
- Verify relief valve operation
- Inspect coupling alignment
- Check mounting bolt torque

#### Monthly Maintenance (~160 Operating Hours)
- Lubricate bearings if required
- Inspect shaft seal for weeping
- Check gasket integrity
- Record performance data for trend analysis
- Clean exterior of pump housing

#### Quarterly Maintenance (~500 Operating Hours)
- Measure bearing play: should be less than 0.003 inches; warning at more than 0.005 inches
- Measure gear tooth profile for wear
- Inspect bearing condition
- Pressure test relief valve
- Check all piping connections for tightness

#### Annual Overhaul (~2,000 Operating Hours)
- Full disassembly and inspection
- Replace all elastomers and wearing parts using NAPCO repair kit
- Verify housing and shaft condition
- Reassemble, prime, and test

#### Signs It's Time to Rebuild
- Reduced flow rate: 10–20% reduction = early wear; more than 20% = rebuild needed
- Increasing motor amperage at same operating conditions
- Visible or audible seal leakage
- Unusual noise (rumbling, grinding, cavitation)
- Excessive temperature
- Loss of prime
- Bearing play exceeding 0.005 inches

---

### Field Maintenance Guide for Rotary Gear Pumps

URL: https://www.napcopumps.com/resources/field-maintenance-rotary-gear-pumps

NAPCO pumps are engineered for on-site rebuild with factory-matched repair kits. No factory return required. A trained technician can complete a full rebuild in 2–5 hours in the field (2–4 hours for the PA200 series, 2–5 hours for the PA300 series).

#### What's Inside a NAPCO Repair Kit
- 1 drive gear assembly (gear mounted on its shaft: stainless steel in S kits, ductile iron in C kits)
- 1 idler gear assembly (gear mounted on its shaft)
- 4 roller bearings (PM038)
- 4 high-pressure seals (PM036)
- 4 low-pressure seals (PM037)
- 2 center case gaskets, .016 inch thick
- 3 center case gaskets, .008 inch thick

Not included (rarely wear in normal service): Housing and end covers.

#### When to Rebuild: Warning Signs

1. Loss of flow rate (primary indicator): Compare current GPM at known RPM and pressure to baseline
2. Pressure drop without flow increase: Indicates internal bypass/slip between gears and housing
3. Seal leakage at case drain or shaft
4. Unusual noise or vibration: Rumbling = bearing wear; knocking = gear wear; cavitation = suction problem
5. Excessive temperature rise: suggests internal friction or cavitation
6. Loss of prime: Worn gears no longer create sufficient vacuum

#### High-Level Rebuild Procedure

1. Isolation and drainage: Close inlet/outlet valves, drain pump housing
2. Disassembly: Remove end covers and access gears and bearings
3. Inspection: Measure wear on housing bore, gear teeth, shaft
4. Gear and bearing removal: Pull worn components
5. Seal and gasket replacement: Clean surfaces, install new seals from kit
6. Reassembly: Install new gears, bearings, and seals from repair kit
7. Testing: Prime and test at low pressure before returning to service

#### Troubleshooting

| Symptom | Likely Cause | Solution |
|---------|-------------|----------|
| No flow | Wrong rotation direction | Reverse motor leads |
| No flow | Suction leak | Check all inlet fittings |
| Low flow | Worn gears | Rebuild with repair kit |
| Low flow | Speed too low | Increase RPM |
| Excessive noise | Cavitation | Check suction line, reduce speed |
| Excessive noise | Bearing wear | Replace bearings |
| Seal leak | Seal wear | Replace seals (in repair kit) |
| High amperage | High viscosity | Reduce speed or warm fluid |
| High amperage | Worn bearings | Replace bearings |

#### Tools Required for Field Rebuild
- Socket set (metric and SAE)
- Flathead and Phillips screwdrivers
- Rubber mallet or dead-blow hammer
- Gear puller or bearing removal block
- Torque wrench
- Feeler gauges
- Digital calipers
- Clean rags, solvent, light machine oil
- NAPCO repair kit for pump model
- Waste container for drained fluid

#### Stocking Recommendation for Remote Operations
Stock 2 repair kits per pump model on-site. This allows back-to-back rebuilds and eliminates weeks of downtime waiting for parts to arrive at remote mine sites.

---

## Repair Kits: Finder & Selection

URL: https://www.napcopumps.com/kit

### Kit Selection Guide

| Kit    | Housing       | Compatible Pump | Weight | Typical Applications |
|--------|---------------|-----------------|--------|----------------------|
| PK200C | Ductile Iron  | PA200C          | 28 lbs | Petroleum, lubricants, waste oil, adhesives plant transfer |
| PK200S | Stainless     | PA200S          | 28 lbs | Chemicals, solvents, food-grade fluids, corrosive liquids, emulsion transfer on 2-inch lines |
| PK300C | Ductile Iron  | PA300C          | 34 lbs | High-volume fuel transfer, heavy industrial fluids, adhesives |
| PK300S | Stainless     | PA300S          | 34 lbs | Emulsion explosives / ammonium nitrate blends, chemical transfer, corrosive high-volume duty |

All kits ship in a 12 x 18 x 6 inch carton.

### What's in Every Kit
- Drive and idler gear assemblies on matching shafts (ductile-iron shafts in C kits; induction-hardened stainless shafts in S kits). Standard working gears are nitrile. Viton optional where approved.
- Roller bearings: PM038, 4 per kit
- Mechanical seals: PM036 high-pressure and PM037 low-pressure, 4 each
- Centercase gaskets: PM007G01 0.008 inch (qty 3) and PM007G02 0.016 inch (qty 2)
- Cover bolt o-rings: PB43, qty 4
- Not included: wear plates, assembly lubricant, housing, end covers

### When to Rebuild
- Declining flow at normal operating speed
- Increased noise or vibration
- Visible leakage at shaft seal
- Higher-than-normal motor power draw

Lead times vary. Please contact us for current lead times.

---

## About NAPCO

URL: https://www.napcopumps.com/about

NAPCO (North American Pump Company, L.L.C.) was founded in 1995 in Sandy, Utah. The company manufactures rotary gear pumps and factory-matched repair kits for industrial fluid transfer.

NAPCO's philosophy: Build tougher, simpler, easier-to-service pumps than the alternatives. Every pump is precision-machined, hand-assembled, and tested before shipping. NAPCO does not try to be everything to everyone: it focuses exclusively on rotary gear pumps and does that exceptionally well.

Global reach: NAPCO pumps operate across six continents. End users in mining, explosives manufacturing, chemical processing, petroleum distribution, food production, and general industrial manufacturing worldwide.

Direct sales model: NAPCO sells direct to end users and OEMs. No distributor markup. Email-based workflow, payment in advance, customer-arranged freight.

What NAPCO manufactures:
- Rotary Gear Pumps: PA series in 2-inch and 3-inch port sizes
- Repair Kits: PK series factory-matched kits for all pump models

---

## Additional Resource Pages

### Rotary Gear Pumps in Explosives & Mining

URL: https://www.napcopumps.com/resources/rotary-pumps-explosives-mining

Technical guide to rotary gear pumps for explosives manufacturing and mining operations. Emulsion explosives transfer, viscosity control, field serviceability.

---

### Gear Pump Cavitation Troubleshooting & Prevention

URL: https://www.napcopumps.com/resources/gear-pump-cavitation-guide

Complete guide to gear pump cavitation: causes, symptoms, prevention strategies, and how to size suction lines correctly to avoid vapor bubble collapse.

---

### Rotary Gear Pump vs. Centrifugal Pump

URL: https://www.napcopumps.com/resources/rotary-gear-pump-vs-centrifugal-pump

Comparison of rotary gear pumps and centrifugal pumps: when to use each technology, head-to-head analysis, and why gear pumps excel for viscous fluids.

---

### Stainless Steel Gear Pumps for Food Processing

URL: https://www.napcopumps.com/resources/stainless-steel-gear-pumps-food-processing

Selecting stainless steel gear pumps for food processing: material compatibility, cleanability, and viscosity considerations.

---

### Pump Repair Kit vs. Replacement

URL: https://www.napcopumps.com/resources/pump-repair-kit-vs-replacement

When to rebuild a gear pump with a repair kit versus buying a new pump: cost comparison, downtime analysis, and a decision framework.

---

### High-Viscosity Pump Selection for Adhesives

URL: https://www.napcopumps.com/resources/high-viscosity-pump-selection-adhesives

Technical guide to pump selection for high-viscosity adhesives, sealants, and resins. Viscosity fundamentals, temperature management, pump sizing.

---

### Rotary Gear Pump

URL: https://www.napcopumps.com/resources/rotary-gear-pump-working-principle

How a rotary gear pump works: positive displacement, gear meshing, flow vs pressure, and viscosity. Technical guide from NAPCO.

---

### Positive Displacement Pumps: Gear, Vane, Piston

URL: https://www.napcopumps.com/resources/positive-displacement-pump-comparison

Comprehensive comparison of positive displacement pump types: gear pumps, vane pumps, and piston pumps. Learn strengths, weaknesses, and when to choose each.

---

### Gear Pump Troubleshooting Guide

URL: https://www.napcopumps.com/resources/gear-pump-troubleshooting-guide

Complete gear pump troubleshooting guide. Diagnose no-flow, low pressure, excessive noise, seal leaks, overheating, and vibration with step-by-step fixes.

---

### PA200S 2" Stainless Steel Gear Pump

URL: https://www.napcopumps.com/resources/pa200s-stainless-steel-gear-pump

Complete spec guide for the NAPCO PA200S 2-inch stainless steel gear pump. Flow rates, pressure, gear options, applications, model variants, and FAQ.

---

### How to Rebuild a Rotary Gear Pump

URL: https://www.napcopumps.com/resources/gear-pump-rebuild-guide

Complete field rebuild guide for NAPCO PA200 and PA300 rotary gear pumps. Repair kit contents, tools, a 12-step procedure, gear clearance, and torque specs.

---

## Contact & Ordering

URL: https://www.napcopumps.com/contact

NAPCO sells direct. No distributors, no dealers.

To request a quote or get a pump recommendation, contact:
- Email: taylor@napcopumps.com
- Phone: (801) 382-8881
- Website: https://www.napcopumps.com/contact

When requesting a quote, provide:
- Fluid type and viscosity (cSt or cP)
- Required flow rate (GPM)
- System pressure (PSI)
- Operating temperature (°F)
- Port size preference (2-inch or 3-inch)
- Material requirements (food-grade? corrosive fluid?)

Lead times vary. Please contact us for current lead times. Payment in advance. Customer-arranged freight.

---

## Frequently Asked Questions

URL: https://www.napcopumps.com/faq

**What fluids can NAPCO rotary gear pumps handle?**
NAPCO pumps handle a wide range of viscous and non-viscous fluids: petroleum products, emulsion explosives, adhesives, solvents, chemicals, food-grade oils, paints, coatings, and more. Contact NAPCO with your specific fluid for a compatibility confirmation.

**What is the maximum pressure rating?**
100 PSI maximum tested operating pressure for all models. Always install a relief valve or bypass: gear pumps are positive displacement and will build pressure until something fails without a pressure relief path.

**Are NAPCO pumps bi-directional?**
Yes. Reversing the direction of shaft rotation reverses the flow direction. This is particularly valuable for loading/unloading operations: pump from tank A to tank B, then reverse to return unused material.

**How long does a rebuild take?**
A trained technician can complete a full field rebuild in 2–5 hours using a NAPCO factory-matched repair kit. No special equipment or factory return required.

**What is included in a repair kit?**
1 drive gear assembly, 1 idler gear assembly (gears pre-mounted on their shafts: induction-hardened stainless steel in S kits, ductile iron in C kits), 4 roller bearings, 4 high-pressure seals, 4 low-pressure seals, and 5 center case gaskets (2 at .016 inch, 3 at .008 inch). The housing and end covers are not included: they rarely wear in normal service.

**What is the lead time for new pumps and repair kits?**
Lead times vary. Please contact us for current lead times. NAPCO operates on a payment-in-advance basis with customer-arranged freight.

**What size pump do I need?**
Depends on your required flow rate (GPM), system pressure (PSI), and fluid viscosity. The PA200 series delivers up to 69 GPM; the PA300 series delivers up to 158 GPM. See the pump sizing guide at https://www.napcopumps.com/resources/how-to-size-rotary-gear-pump or contact NAPCO directly.

**Do I need nitrile or Viton gears?**
Nitrile is the standard option and works for petroleum, emulsions, water-based fluids, and most adhesives. Choose Viton if your fluid contains aromatic solvents, chlorinated solvents, strong oxidizers, or if operating temperatures exceed 240°F. See the full guide at https://www.napcopumps.com/resources/nitrile-vs-viton-gears.

**Stainless steel or ductile iron?**
Choose stainless steel (PA-S models) for corrosive fluids: ammonium nitrate emulsions, acids, solvents, food-grade applications. Choose ductile iron (PA-C models) for non-corrosive fluids: petroleum, adhesives, paints, lubricants. See the guide at https://www.napcopumps.com/resources/stainless-steel-vs-ductile-iron-pumps.

---

*Last updated: July 2026. For the most current information, visit https://www.napcopumps.com or contact taylor@napcopumps.com.*