Installation Tips and How to Test a Diaphragm Pump

Figure 1: Diaphragm pumps.

When installing a pneumatic diaphragm pump, anyone who is not familiar with pumps and pump installations will often make small mistakes that result in costly damages.

1. Installation Tips

Here are some useful tips that will save you having to learn the hard way.
1) The diaphragm pump must be mounted onto a rigid baseplate.
2) The suction port size must never be reduced.
3) The suction pipe or hose must never be smaller than the suction port size.
4) The suction pipe or hose must be as short as possible and preferably never more than 5 meters.
5) The discharge pipe can be reduced subject to design requirements within reason.
6) The pump must have a dedicated air filter/regulator installed.
7) The air pressure must be regulated to 2 bar on the first startup, especially if the pump is fitted with TEFLON diaphragms.
8) A cycle speed of 60 to 70 cycles per minute is ideal for long life and a low cost of ownership.

2. How to Test It

2.1 Safety First

Figure 2: Check all connections of the pump.

● Check that original manufacturers spare parts have been used – non-original parts can be dangerous and will invalidate any warranty or certification issued on the pump.
● Check all connections are tight and have been correctly torqued as per manufacturer’s instructions.

2.2 Test with Vacuum Gauge

● Connect a vacuum gauge to the pump inlet – turn the air on to the pump – check the vacuum reading is as the vacuum on the manufacturer’s literature.
● Turn off the air to stop the pump.

Figure 3: Vacuum gauge.

2.3 Pump Operation

● Connect the pump via suitable pipework to a liquid source (Clean Water) and connect up an outlet to the pump either taking the liquid to recirculating tank or to drain where applicable.
● Ensure you have a valve in the outlet pipework.
● Start the pump slowly to prime and build up speed until the pump is running as the speed required on the application.
● Pump should be cycling evenly, pumping the liquid.

2.4 Pump Integrity

● While operating the pump at its maximum flow / pressure; slowly close the valve in the outlet pipework until the pump stops running. This is when the liquid pressure in the outlet pipework reaches the same pressure as the air pressure being given to the pump.
● Inspect the pump, paying special attention to the body / manifold seals as well as the Diaphragm seals, for leaks.
● Once the inspection is complete slowly open the valve in the delivery pipework, the pump will start cycling again once the pressure in the delivery pipework drops.
● Turn off the air to stop the pump.

Figure 4: Inspect the pump carefully.

2.5 Draining The Pump

● Pump can be run without connection to the liquid source, this will pump most of the liquid out of the pump.
● Further liquid can be drained out by tipping the pump where applicable and safe to do so.
● Warm air can be passed through the pump if required to fully dry the pump.

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