Diaphragm PumpFAQ April 2026 Antlia Engineering Works
10 Frequently Asked Questions About Diaphragm Pumps
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Audio version — 10 FAQs About Diaphragm Pumps
Here are 10 of the most frequently asked questions about diaphragm pumps — covering material compatibility, acid handling, FRL units, pressure limits, flow regulation, submerged operation, diaphragm life, viscosity limits, and warranty. These answers apply to Antlia's full range of AODD pumps.
1
What if the chemical to pump/diaphragm MOC (material of construction) compatibility has a 'B' rating?
Antlia does not recommend anything other than 'A' rated combinations. The warranty of Antlia pumps will be lapsed for any chemical-to-material rating of 'B'.
Important: Always verify your chemical is rated 'A' against the pump body material, diaphragm material, and valve ball material before ordering. Contact our team for a compatibility check — free of charge.
2
Can acids be pumped using Polypropylene (PP) diaphragm pumps?
Yes. Acids can be pumped using PP (Polypropylene) diaphragm pumps after consulting a chemical compatibility guide for concentration and temperature limits.
Note: PP pumps are compatible with many dilute acids. For concentrated acids or high-temperature acid applications, SS-316 or PVDF pump bodies may be recommended. Always check chemical compatibility before use.
3
What is an FRL (Filter-Lubricator-Regulator) unit? What purpose does it serve?
Air leaving a compressor is hot, dry, or wet — which can damage and shorten the life of downstream equipment such as pumps and valves. Before compressed air can be used, it needs to be filtered, lubricated, and regulated.
An FRL unit performs all three functions: the Filter cleans the compressed air by removing moisture, dust, and debris; the Regulator sets and maintains the correct operating pressure; and the Lubricator adds a fine mist of oil (SAE 40) to keep internal air valve components running smoothly.
Recommendation: Always install an FRL unit between your compressor and AODD pump. It is the single most effective way to extend pump life and prevent stalling. Learn more about FRL units →
4
Can an AODD pump be operated at a pressure higher than the recommended maximum?
No. Operating above the recommended maximum pressure (7 bar for Antlia AODD pumps) can cause serious damage:
The pump may start leaking at connections and seals
Diaphragms may bulge or wear prematurely
Inner plates and structural components may bend
Always install a pressure regulator in the air supply line to prevent over-pressurisation. Recommended operating range: 4–6 bar. Maximum: 7 bar.
5
How do I regulate the flow of a diaphragm pump?
You can regulate the flow of an AODD pump in two ways:
Using the regulator on the FRL unit to increase or decrease the volume of air going to the pump — more air = higher flow, less air = lower flow
Using a flow control valve on the air inlet line for finer flow adjustment
Key Point: AODD pump flow is directly proportional to air pressure — adjusting the regulator gives you full, stepless control over the pump's output without any electrical controls.
6
Can an air operated diaphragm pump be submerged?
Yes, absolutely — with two conditions:
The chemical must be compatible with the pump's MOC (material of construction) and housing
The air exhaust pipe must be above the level of the fluid to prevent liquid back-flow into the air valve
Submerged operation is common in sump emptying, pit drainage, and tank emptying applications. The AODD pump's lack of electrical components makes it intrinsically safe for submerged use.
7
The pump was working properly but has slowed down and is not getting the required capacity. What should be done?
If the pump has slowed down or lost flow capacity, check the following in order:
Check suction and discharge lines for any blockage or obstruction
Check valve seats for dust, scale, or remaining fluid deposits that may prevent full ball seating
Check the FRL filter bowl — a clogged filter restricts air flow and reduces pump speed
Check the air inlet pressure — a drop in compressor pressure will directly reduce flow
8
What is the life of diaphragms in an AODD pump?
Diaphragm life depends on many variables. Inspection every 4–6 months is recommended for continuous duty operations.
The major factors leading to diaphragm failures are:
Pressure — operating above the recommended maximum accelerates wear
Temperature — pumping fluids at temperatures outside the diaphragm material's rating
Moisture — wet, unfiltered air can degrade diaphragm material over time
Chemical incompatibility — using a 'B' rated chemical-to-diaphragm combination
Keep a spare diaphragm set on site for your pump model. Antlia supplies genuine spare diaphragms for all Antlia AODD pump models.
9
What is the maximum viscosity an AODD pump can handle?
12,000 CPS (centipoise) is the maximum viscosity recommended under ideal conditions for Antlia AODD pumps.
For highly viscous materials approaching this limit, ensure you use a pump with large ball check valves, keep the suction line short, and lower operating speed (reduce air pressure) to give the fluid time to flow into the pump chamber. Read our full guide on viscous material pumping →
10
What is Antlia's pump warranty?
Antlia offers a 1-year warranty against manufacturing defects from the date of purchase.
This warranty does not include diaphragms, as they are consumable parts of the pump — their lifespan depends on the application, fluid, pressure, and temperature conditions.
Note: Warranty is also voided if the pump is operated with chemical-to-material combinations rated below 'A', or operated above the recommended maximum air pressure of 7 bar.
Have more questions about our AODD pumps?
Our engineers at Antlia Engineering Works, Mumbai are happy to answer any technical questions about pump selection, material compatibility, and operation — free of charge.
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