Section 9
Vacuum Pump Rebuild B R&P 2000 FRM PM 2.5
1.0Safety Notice: Properly trained personnel should only attempt repair of this instrument. High voltages may be present in pump enclosure. The possibility of shock or electrocution exists. Use established safety precautions when attempting this procedure.
Do not attempt this procedure in the field. The air sampler should be brought into a shop setting where proper tools and methods can be used.
2.0Vacuum Pump Removal: This procedure describes the method of removing the vacuum pump from the R&P 2.5 FRM Air Sampler. Caution: Make sure that electrical power to this instrument is disconnected before attempting this procedure. Failure to do so may result in severe shock hazard or electrocution.
2.1Open the air sampler door to reveal the display panel, Wins Impactor and bottom face plate.
2.2Remove the lower front faceplate by removing the 4 screws. You will now be able to see the vacuum pump, which is the grey cylindrical apparatus that has two hoses connected to the top.
2.3Remove the electrical wire connection of the pump from the bottom of the Interface Board, which is labeled (Pump), by pressing on the plastic connection lock and then pulling straight down (Figure 1).
2.4Remove the ground wire from the grounding lug that is located to the left of the pump.
18
2.5Remove both vacuum lines from the top of the pump. This is accomplished by placing the tip of a flat screwdriver or a wrench on the top of the chrome CammozziJ push connect fitting and pushing in, while at the same time pulling the vacuum hose out of the fitting (Figure 2).
2.6Remove the four anchor nuts, which hold the pump to the housing. The pump can now be removed from its enclosure.
3.0Vacuum Pump Overhaul: The following procedure describes the method of removal and installation of the intake and exhaust vacuum valves and the vacuum diaphragm and gasket.
Note: It is a good idea to draw out your disassembly process onto a piece of paper; this will serve as a good reference and help eliminate reassembly errors.
3.1Place the vacuum pump on a sturdy workbench to begin disassembly of the pump. Note: Unless you are an experienced technician, do not try to repair both cylinders at the same time. It is too easy to become confused as to the position of the intake and exhaust valves. You can use the other cylinder as a reference guide.
3.2Remove the 4-#10 Phillips head screws from the first cylinder head. Note the direction of the exhaust filter on the head and the position of the head on the pump. The pump head is symmetrical and can be reassembled incorrectly.
3.3Place the top head cover upside down on the workbench. You will see a round plate that has four recessed flathead screws and a thin metal flap which is the Valve Plate. Note the direction of the valves (the thin metal flap) and the position of the valve plate before removal. There are two chambers underneath the valve plate, one is a vacuum intake chamber and the other is an exhaust chamber. The valve plate is also symmetrical and can be installed incorrectly. The pump will not work if any of these parts are installed incorrectly.
18
Important:The (intake) chamber is the one that has the compression hose fitting threaded into the side. The (exhaust) chamber is the one with the brass filter threaded into it(Figures 3 & 4).
3.4Remove the four recessed flathead screws.
3.5Remove valve plate from the head.
18
3.6Remove the old rubber gasket from around the two chambers and install the new gasket exactly as the old one.
3.7Remove the intake valve by removing the flathead screw. Install the new valve in the same location and direction. Torque to 10in pounds.
3.8Turn the valve plate over and remove the exhaust valve. Install the new valve in the same location and direction. Torque to 10in pounds.
3.9Reattach the valve plate onto the head, making sure the intake and exhaust valves are located in the correct chambers. Torque to 10in pounds in a cross pattern. Once completed, set the head and valve assembly aside.
3.10You are now ready to replace the vacuum diaphragm. Remove the 4 Phillips head screws from the round diaphragm plate that holds the diaphragm to the piston (Figure 5).
3.11Remove the diaphragm from the piston.
3.12Looking down at the metal piston of the vacuum pump, determine if the cylinder gap is equal around the head of the piston making sure the piston does not rub the cylinder wall. If the piston and the gap look okay, install the new diaphragm and the plate to the piston; torque to 20in pounds. If the gap is not equal, follow steps 3.13 - 3.14.
18
3.13Remove the plastic protective fan cover from the front of the vacuum pump. This is accomplished by removing the four flathead screws (Figure 6).
18
3.14Position the vacuum pump so you can see the two adjustment holes in the side of the pump housing. The top hole is used to tighten and adjust the Counter-Balance Weight. The bottom hole is used to adjust the piston gap by loosening the Allen screw and moving the piston rod forward or backwards on the sealed bearing. Once the gap is equal around the piston, tighten the Allen screw then attach the plastic protective fan cover back onto the vacuum pump (Figures 7 & 8).
3.15Inspect to see that the diaphragm and the valve head match up and that the diaphragm is not being pinched or off center, then reattach the diaphragm to the piston.
3.16Reassemble the valve head to the vacuum pump; torque the four screws to 20in pounds.
3.17Repeat the above steps for the other vacuum pump cylinder.
18
4.0Vacuum Pump Check: This procedure determines if the vacuum pump was rebuilt correctly or incorrectly. Once both cylinders have been rebuilt and reassembled there must be a vacuum check on each cylinder.
4.1Install a vacuum gauge to the first cylinder to be tested (Figure 9).
4.2Connect the power supply connector of the vacuum pump to the Interface Board (Figure 1).
4.3Connect the air sampler to main power.
4.4Turn on the power to the air sampler.
4.5Make sure the air sampler is in the Stop Mode.
4.6Press the F-5 Setup button to enter the Calibration Screen.
4.7Press the F-2 Flow Cal button to enter the Flow Calibration Screen.
4.8Press the F-2 Start button twice to start the vacuum pump.
4.9Each cylinder must have 22ins Hg of vacuum for the pump to pass and be used for service. If there is not 22ins Hg, then the pump was not rebuilt correctly.
Note:It is the responsibility of the technician to determine if the vacuum pump can be rebuilt or not. If the vacuum pump has been rebuilt several times before, it may be more sensible to purchase a new pump from the manufacturer.
18
5.0Vacuum Pump Installation: This procedure describes the method of installing the vacuum pump into the R&P 2.5 FRM Air Sampler.
5.1Disconnect main power to the air sampler.
5.2Place the vacuum pump into the pump compartment with the exhaust filters facing inward and the hose fittings facing outward.
5.3Tighten the four mounting nuts on the vacuum pump.
5.4Insert the vacuum hoses into the CammozziJ push connect fittings.
5.5Tighten the ground wire back on the grounding lug.
5.6Install the pump compartment faceplate using the four #10 flathead screws.
5.7The air sampler should now be ready for a test run.
18