Dosing Pump Chemical Compatibility Chart

Why Wetted Material Selection Matters

A dosing pump's performance rating means little if its wetted parts — the pump head, diaphragm, and valve balls — aren't chemically compatible with the fluid being dosed. Incompatible materials degrade quickly, leading to leaks, inaccurate dosing, and unplanned downtime. Here's a practical reference for the most common water treatment chemicals.

Compatibility Reference Chart

Chemical	Recommended Pump Head	Recommended Diaphragm/Seal
Sodium Hypochlorite (bleach)	PVDF or PVC	PTFE or Viton
Alum / Ferric Chloride (coagulants)	PVC or PP	PTFE
Polymer / Flocculant	PP or PVC	EPDM or PTFE
Sulphuric / Hydrochloric Acid (pH correction)	PVDF	PTFE
Sodium Hydroxide (caustic)	PP or PVC	EPDM or PTFE
Antiscalant	PVC or PP	PTFE or EPDM
Sodium Bisulphite (dechlorination)	PVC or PP	PTFE

This chart is a general starting reference. Concentration, temperature, and exact chemical grade affect compatibility — always confirm with your chemical supplier's material safety data sheet (MSDS) and QuaSys's technical team before final selection.

PTFE: The Safe Default for Aggressive Chemicals

PTFE (Teflon) diaphragms resist nearly all common water treatment chemicals and are the safest default choice when in doubt. The tradeoff is cost — PTFE diaphragms are more expensive than EPDM, so for mild chemicals like polymer or antiscalant, EPDM is often a cost-effective and perfectly compatible choice.

Signs of Wrong Material Selection

Diaphragm swelling or softening — visible bulging, reduced pump output over time
Pump head cracking or discolouration — especially around chemical contact surfaces
Valve ball degradation — irregular or declining dosing accuracy despite consistent settings
Frequent leaks at seals — chemical attack on gasket materials

QuaSys Inc. supplies Toshcon and SEKO dosing pumps in a full range of wetted material configurations matched to your specific chemical. Tell us what you're dosing and we'll recommend the right pump head and diaphragm material, or call +91 95408 15659.

Frequently Asked Questions

Can I use a standard PVC pump head for sodium hypochlorite?

PVC is generally acceptable for sodium hypochlorite at typical water treatment concentrations (up to around 12-15%), but PVDF offers better long-term resistance, especially at higher concentrations or elevated temperatures. For continuous, high-duty hypochlorite dosing, PVDF is the safer long-term choice.

What happens if I use the wrong diaphragm material?

The diaphragm will degrade faster than expected — softening, swelling, or cracking — leading to reduced dosing accuracy, leaks, and eventually diaphragm failure. This typically shows up as inconsistent chemical dosing well before a complete failure, so declining treatment performance is often the first warning sign.

Do all dosing pump chemicals need special materials, or is standard PVC usually fine?

Mild chemicals like polymer, antiscalant, and dilute caustic generally work fine with standard PVC/PP heads and EPDM diaphragms. Aggressive chemicals — concentrated acids, hypochlorite, and oxidizers — need PVDF heads and PTFE diaphragms for reliable long-term service.