Choosing a Pump Head Material: PP, PVC, PVDF, SS316 or PTFE on NEWDOSE Dosing Pumps
A pump head that turns chalky or starts flaking after six months, valve seats that warp and stop sealing, flow that keeps dropping. Nine times out of ten that's a pump head material problem, not a pump problem. NEWDOSE sells its metering pumps as corrosion-resistant with adjustable flow, but how well they resist depends on which head set you put on them.
The Pump Head Set Is More Than the Head
What NEWDOSE calls the pump head material set is a full package: head, diaphragm, valve seats, valve balls and seal. The five combinations on the solenoid pumps are:
- PPV: PP head, PTFE diaphragm and seats, ceramic balls, FKM seal;
- PVT: PVC head, the rest as above;
- PVDF: PVDF head, the rest as above;
- SST: SS316 head, with SS316 seats and balls, PTFE diaphragm, FKM seal;
- PTFE: head, diaphragm and seats all PTFE, ceramic balls, no seal.
The diaphragm is PTFE in every set. What really changes is the head, the seats and balls, and the seal. So when you check chemical compatibility, don't stop at the head. Ask whether the FKM seal and ceramic balls can take the same chemical.
How to Pick a Pump Head Material
This is the reasoning we use during selection. It's general experience, so the exact chemical and concentration still need checking line by line.
Plastic heads: PP, PVC, PVDF
PP and PVC are inexpensive and handle most dilute acids, dilute alkalis and salt solutions. PVC is also a common pump head material for water treatment chemicals such as sodium hypochlorite and PAC. PVDF is a clear step up from PP and PVC in chemical and temperature resistance. When the concentration is high or you're unsure, moving to PVDF is the safer bet.
The shared weak spots of plastic heads are temperature and pressure. If the chemical runs warm, or the injection pressure gets close to the pump's rating, check with the factory first.
Stainless steel: SS316
SS316 is strong and handles heat well, which makes it a good pump head material for solvents, oils and some organic chemicals. It's not universal, though. For chloride-bearing chemicals such as hydrochloric acid and sodium hypochlorite, stainless heads are generally not recommended. The HND high-pressure pump comes only in SS316, which is exactly why you check the medium first.
All-PTFE: the fallback
PTFE is stable with almost every common chemical and needs no FKM seal, so it suits strong oxidizers, complex mixtures, or media that also attack fluoroelastomer. The trade-off is a higher price, and threaded connections only.
Which Series Offer Which Pump Head Material
Not every series offers all five. Match them up when selecting:
- Solenoid pumps DFD, DP, DM and DC: PP, PVC, PVDF, SS316 and PTFE are all available;
- Mechanical pumps NDJ, NDWS and NDWL: PVC, PVDF, PTFE and SS316;
- Mechanical pumps ND1000 and ND2000: the literature lists only PVC, PTFE and SS316;
- HND high-pressure pump: SS316 only;
- Evodose stepper pump: PVC as standard, with PVDF, PTFE and SS316 as options.
In other words, PVDF on the high-flow mechanical pumps, or PP on anything other than a solenoid pump, needs a separate question to the factory.
Connections Change With the Material
The pump head material also affects how you connect. On NDJ and NDW pumps, PVC and PVDF heads offer a DN15 solvent-weld socket for rigid pipe in addition to the G1 thread. PTFE and SS316 heads are threaded only.
Solenoid pumps have 1/2 G parallel threads on suction and discharge. The manual specifically warns against wrapping PTFE tape straight onto the pump head thread and screwing it into a female fitting. Over time it leaks, and with aggressive chemicals that gets messy. For rigid PVC pipe, the factory can supply a rigid pipe adapter that takes DN15 pipe directly.
For chemicals that gas off easily, like sodium hypochlorite and hydrogen peroxide, mount the pump below the tank level so the chemical floods the head. Combined with a head that has a degassing valve, that avoids most air locks.
Don't Ignore the Adjustable-Flow Half
Corrosion resistance decides whether the head survives. Adjustable flow decides whether the dose is right. Solenoid pumps adjust stroke rate from the panel anywhere from 0 to 100%. Mechanical pumps use a stroke handwheel that works while running, and can take an electric stroke actuator on 4–20 mA. The pump head material doesn't change how you adjust, but it does affect valve choice.
Mechanical pumps can be fitted with a multifunction check valve that uses a PTFE elastic element instead of gravity return. It brings three benefits: steadier output and linearity with viscous chemicals, some back pressure at the discharge when the element is adjusted, and when set to suit line pressure it can double as a relief valve. The element itself is PTFE, so it holds up well against thick, corrosive chemicals.
Put These Details on Your Inquiry
Getting the pump head material right depends on complete information. At a minimum, the inquiry should state the chemical name and concentration, temperature, whether it carries particles or crystallizes, and injection pressure. Write only "acid" or "chemical" and the factory can only quote the most common configuration, which raises the odds of trouble later.
Conclusion
Whether a NEWDOSE corrosion-resistant metering pump actually resists corrosion comes down to the whole head set. The head sets the baseline, while seats, balls and seal decide the details. Typical water treatment chemicals go on PVC or PVDF, chloride chemicals stay away from stainless, solvents and oils can use SS316, and complex media fall back on all-PTFE. Check the pump head material against what each series offers and how it connects, and the choice will hold up.
FAQ
Can I change the pump head material later on the same pump?
Head sets are supplied to match the model code. Ask the factory whether parts are interchangeable before changing, and don't mix parts of different materials yourself.
Is the clear suction tubing fine for long-term use?
The standard kit is clear PVC suction tubing and semi-clear PE discharge tubing, which suit typical chemicals. For unusual media or outdoor sun exposure, ask the factory about other tubing.
PVDF or PTFE, which is better value?
For most water treatment and common acids and alkalis, PVDF is enough and costs less. All-PTFE only earns its price when the medium is very complex or attacks the FKM seal.
Can a stainless head pump sodium hypochlorite?
Generally not recommended. Chloride chemicals risk corroding stainless. Sodium hypochlorite usually runs on PVC or PVDF heads.
What if the chemical is hot?
A plastic pump head material has a temperature limit, and the literature gives no single figure. If the chemical is clearly above room temperature, send the temperature with the chemical to the factory to confirm the pump head material.
If you're not sure which head your chemical needs, send the name, concentration and temperature through our contact page and we'll check it item by item.