NAPCO Repair and Installation Procedure
Periodic Inspection of Internal Working Parts
Periodically, or upon indication of loss of performance, pump can be easily opened, inspected and cleaned by following steps 2.1 and 2.2 below.Follow the applicable steps under 2.3 to reassemble pump.
Quick Internal Inspection and Pump Cleanout
- Close valves, lock out drive.
- The non drive bearing housing/side cover may be removed to remove blockages and/or inspect for damage.
Inspection and/or Repair of Pump
Step 1: Disassembly
- Remove non drive bearing housing/side cover.Bearing housing/side covers have 2 bolts with washer & O-rings.Note location for reassembly. Caution, do not damage gaskets.Note how many on each side.
- Remove top idler gear, pull by hand.
- Remove drive gear.Take care during shaft removal not to damage seals with sharp keyway.
- Unbolt and remove drive side bearing housing/side cover. Take care not to damage gaskets.
- Remove bearing grub screws and bearings.
- Remove high and low pressure seals, note orientation for correct reassembly.
Step 2: Clean and Inspect
- Clean all pump parts of product and old grease.
- Inspect all parts, particularly:
- Gear rubber for excessive wear or damage.
- Bearings, seals, gaskets, grease nipples for rust, wear, damage
Step 3: Reassembly
- Install 4 bearings: insert from external side of bearing housing/side cover using bearing tool NAPT0001.Secure with set screws with loctite 222 on threads, then back off set screws 1⁄4 turn.
- Install 4 low pressure seals: grease seal OD and ID and insert from pump side of bearing housing/side cover using tool NAPT0003 till seal seats on lower shoulder.Be sure that open side of seal faces away from tool. Pre stretch seal ID with tool NAPT0005.
- Install 4 high pressure seals: grease seal OD and ID and insert from pump side of bearing housing/side cover using tool NAPT0002 until flush with upper shoulder.Be sure that open side of seal faces tool.Pre stretch seal ID with tool NAPT0005.
- Fit 1 x .016” or 0.4 mm. drive side gasket by adhering to bearing housing/side cover with grease. Note: bearing housing/side covers can be oriented to provide best access to grease nipples with pump in service.
- Fit drive side bearing housing/side cover, align with aligning pins, secure housing cover with 12 bolts tightening evenly to 35 ft/lbs. or 48 Nm. Remember that the two recessed bolts have washers and O-rings. Install gear assemblies. Grease both sides of shafts. Take care not to damage seals when inserting shafts through the seals in the bearing housing/side covers –particularly with sharp keyway edges.
- Adhere 2 x .008” (0.2mm.) gaskets to remaining bearing housing/side cover, locating over alignment pin.
- Mount the remaining bearing housing/side cover by sliding cover onto the protruding gear shafts.Take care not to damage seals, particularly with sharp keyway edges.
- Secure bearing housing/side cover to the pump center case with 4 equally spaced bolts, torque to 35 ft/lbs. or 48 Nm. Important: set the gap between gears and pump bearing housing/side covers to .006” to .008” or 0.1524mm. to 0.218mm. ie a small amount for gear free play. This is achieved by forcing each gear to one side by tapping the gear shaft, set depth gauge to ‘0’ then forcing gear shafts to the other side and note length of travel.Adjust free play by adding or removing gaskets.
- Fit bearing housing/side cover when free play is correct and secure all 12 bolts to 35 ft/ lbs or 48 Nm.
- Grease all bearings (one stroke) and seals (7 strokes) with high quality bearing grease.Evidence of grease should be present in the weep hole and around the bearing seal.
- Rotate gears by hand. They should not bind.
- Important: ensure any drive coupling has free play to provide gear free play within the pump and the drive does not force the gear to one side.
- Fit any guards.
Step 4: Prime and Test Pump
- Run the pump and ensure prime. It may be necessary to use the air bleed valve to achieve initial prime.
- Check for any abnormal noises or sound of gears rubbing or slapping which would indicate the pump having run dry or without product.