The three plastics buyers actually choose between
When engineers say “plastic nozzles,” they are rarely talking about one material. Three thermoplastics do almost all the corrosive-duty work, and they sit on a clean ladder: polypropylene (PP) is the cheap generalist, PVDF is the temperature-and-oxidiser step-up, and PTFE is the chemical-resistance ceiling you reach for only when nothing else lives. The mistake is specifying by habit — defaulting to PP because it is cheap, or to PTFE because it is “the best,” when the medium only needed the middle rung. This guide gives you a path to pick the right plastic nozzle the first time.
Temperature ceiling is the first filter
Start with temperature, because it is the hard wall that eliminates options fastest.
PP is practical to about 60 to 80 degrees C. Push it past that and it softens, creeps under load, and the orifice you specified slowly becomes a different orifice. For the bulk of room-temperature and mildly warm acid, alkali and salt duties, that window is plenty.
PVDF extends the ceiling to roughly 120 to 140 degrees C. That single jump is why it is the default upgrade: many duties are chemically fine for PP but run too hot for it, and PVDF closes the gap without leaving the thermoplastic world.
PTFE spans the widest temperature range of the three and stays stable where the others soften. But temperature headroom is not free — PTFE is mechanically the weakest and creeps under sustained load (cold flow), so you pay for that range in strength and joint care.
Rule of thumb: find your continuous operating temperature, add the safety margin for surges, and let that number cut the list before you think about chemistry at all.
Chemical resistance: where each one wins and loses
Within their temperature windows, the three divide by what they survive.
PP resists a broad spread of acids, alkalis and most salts — the everyday corrosives. It is poor against strong oxidisers and many organic solvents, which is the main reason it is not universal.
PVDF keeps PP’s acid and alkali resistance and adds noticeably better behaviour against oxidisers and halogens (chlorine, bromine and their compounds). That is exactly why it is the workhorse for chloride- and oxidiser-bearing streams that also run warm.
PTFE resists more chemicals than either, across a wider temperature band — it is the material of last resort for the really hostile mixtures. The cost is mechanical: low strength and cold flow, which constrain how you mount and load it.
The selection move is to match the aggressive species in your medium to the polymer that shrugs it off, then confirm the temperature fits. Over-specifying to PTFE “just to be safe” buys chemical headroom you may not need while giving up strength you might.
The cost gradient you pay for temperature
There is a real price ladder here, and it tracks temperature ceiling more than anything else. PP is the low-cost option and is right for the majority of duties. PVDF costs more, and you pay it specifically for the extra temperature and oxidiser resistance. PTFE is the premium, and you earn that premium only in duties where the chemistry or temperature defeats the other two.
Specifying PTFE for a duty PP would have survived is wasted spend; specifying PP for a duty that needs PVDF is a premature failure. The right plastic nozzle is the cheapest one whose temperature ceiling and chemical resistance both clear the medium — no higher.
Mechanical strength and what it costs you
Strength falls as you climb the ladder. PP is the stiffest and most robust of the three in ordinary handling. PVDF is a step down but still solid. PTFE is the softest and most easily deformed; threaded PTFE joints need controlled torque and sometimes reinforcing inserts, because over-tightening or sustained load deforms the thread rather than sealing it.
If the nozzle sees high line pressure, abrasion from suspended solids, or mechanical shock, strength enters the decision. That does not mean abandoning plastic — it means grading the polymer up, or using a plastic body with a hardened or ceramic orifice insert that carries the wear while the polymer carries the corrosion.
Dimensional stability across a header
The property that surprises people is dimensional stability. A metal orifice holds its size; a plastic orifice drifts. Thermal expansion, creep under line pressure, and swelling from fluid absorption all shift the orifice slightly. On one nozzle the effect is usually invisible. Across a forty-nozzle scrubber or spray header, where uniformity is the whole point, those small shifts accumulate into spray-angle and flow scatter you did not order.
Mitigations are straightforward: run well below the material’s temperature limit so creep stays minimal, avoid over-tightening that pre-stresses the polymer, and schedule plastic nozzles as replacement items with a known service life rather than leaving them until they fail. The BoreJet plastic nozzles page lays out the temperature and chemical bands per material so you can pre-check your duty.
A simple selection path
- Get the continuous and peak temperature. If above ~80 C, PP is likely out; if above ~140 C, you are in PTFE territory or a specialty polymer.
- List the aggressive species. Oxidisers or halogens push you from PP toward PVDF. Anything that defeats both pushes to PTFE.
- Check mechanical load — pressure, abrasion, shock. If high, grade up or add an insert.
- Pick the cheapest polymer that clears steps 1–3. Do not buy headroom you cannot name a use for.
That path lands most buyers on PP or PVDF, with PTFE reserved for the genuinely hostile corner.
Reading a chemical compatibility table correctly
Compatibility charts grade a polymer as excellent, good, fair or not recommended for each chemical. The trap is reading only the chemical name and ignoring concentration and temperature. A polymer rated “excellent” for sulphuric acid at 10 percent can be “not recommended” at 90 percent, and the same acid at 80 degrees C may drop the rating a full grade. Always read the table at your actual concentration and temperature, not at the headline chemical. When the chart shows a boundary — “good up to 60 C” — compare your peak temperature, not your average, against it.
PP vs PVDF: the upgrade most buyers face
The decision that comes up most often is not plastic-versus-metal but PP-versus-PVDF, because most corrosive duties are chemically fine for both and the only real question is temperature. The tie-breaker is almost always the operating temperature against PP’s ~80 C ceiling. If your duty runs at 70 C with occasional surges to 95 C, PP will creep and PVDF will not — the upgrade pays for itself the first time you avoid a softened, drifted nozzle. If your duty sits at 50 C and never moves, PP is the right call and PVDF is wasted spend. The rule is boring but reliable: let the peak temperature, not the catalogue, decide.
When none of the three is enough
PP, PVDF and PTFE cover the vast majority of duties, but not all. Very strong oxidisers at high temperature, or certain halogenated solvents, can defeat even PTFE, and then you are looking at exotic polymers or a non-polymer route. The point of this guide is not to force a thermoplastic onto every duty; it is to stop over-specifying PTFE on duties PP handles, and to recognise the narrow corner where you have left the thermoplastic envelope entirely. If your medium sits at that edge, the honest answer is a different class of material, not a thicker plastic nozzle.
If your medium mixes species — say an acid that also runs hot and carries solids — send the full duty to our application team and we will flag the exact polymer and any insert you need before you order.