Air Operated Diaphragm Pump
A - Air Supply
The air supply to an air operated diaphragm pump should be clean, dirt free shop air for minimum maintenance on the pump's air distribution valve assembly.
Currently (1996) there are several air operated diaphragm pumps available that require little or no oil in the air supply. Some of these pumps can operate equally well with or without oil; others are sensitive to even small amounts of oil in the air. Check with the manufacturer or your local vendor to find out how much, if any oil is required for your particular pump.
The air pressure to the pump should be at a pressure greater than the anticipated discharge pressure from the pump.
If the pump will be started and stopped automatically, install an actuated valve after the filter regulator to open/close the air supply.
If the pump's flow rate is to be controlled, provide a globe or other flow flow control style valve in the air supply between the filter regulator and the pump. The object here is to control the rate of flow to the pump, not the pressure. By controlling the rate of air flow to the pump, you will control the liquid flow rate delivered. This type of control will result in a reasonably constant delivery rate from the pump. Several air operated diaphragm pump manufacturer's also offer, as an option, flow control devices that regulate the pump delivery.
Do not restrict the air outlet at the muffler. This can result in shortened diaphragm life. There are rare occasions that restricting the air outlet from the pump may be required, but before attempting this, check with the manufacturer or distributor for guidance.
If the pump is to be operated in areas that have high humidity and the possibility of temperatures below 40 deg. F or 50 deg. F with discharge pressures above 70 to 80 PSI, freezing of the exhaust may occur. If your unit is to be operated in these conditions, an air dryer or non-freeze additive in the air supply may be required.
If pumping a hazardous or toxic chemical, be aware that with diaphragm failure, there is a potential for the chemical to be released from the air outlet connection on the pump.