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КП

Материаловедение проточной части

Головки, мембраны, клапаны и эластомеры дозирующих насосов. Окно подбора — не таблица ASTM, не гарантия и не оферта.

Оценки — для типовых концентраций водоподготовки при комнатной температуре и одной среде. Смеси, нагрев, пульпа и примеси меняют ответ. Инженер подтверждает в КП.

Проточная часть

Что смачивается

Pump head

The chamber that sees the chemical. PVC, PP, PVDF or a metal alloy. The rest of the pump can be painted steel — this cannot.

Diaphragm

PTFE is chemically almost inert but creeps under load. A FKM or EPDM backing takes the mechanical stress. The process sees only the face. Hydraulic oil on HD stays behind that sandwich.

Balls and seats

Check valves set accuracy as much as the stroke. Ceramic and PTFE balls survive oxidizers. SS balls pit in chlorides. Viscous polymer can stick a ceramic ball — that is a rheology problem.

O-rings

The weakest link is often a two-dollar elastomer. FKM for bleach and oils. EPDM for caustic, steam and polymer. PTFE envelope gaskets when neither rubber is honest.

Plunger & packing

Packed plungers are not sealless. Packing weeps by design. Ceramic or Hastelloy rod, compatible packing, lantern ring. Choose HD when leak-free matters more than 350 bar.

Peristaltic tube

On PR the tube is the entire wet-end. No valves to clog on sludge or polymer. Fatigue life is the spare-parts plan. Norprene for chemicals, silicone for sanitary short runs.

Физика и химия

Почему важен полимер или сплав

Pump head, valves, day tanks

PVC

Rigid vinyl. Polar, resists dilute mineral acids, hypochlorite and coagulants. Aromatics, ketones and many solvents craze it.

Окно службы: About 0–50 °C. Softens above that.

Типичный отказ: UV and NaOCl embrittlement over 12–24 months. Not a long-life bleach head — PVDF is preferred.

Heads, tanks, frames

PP

Polyolefin. Strong in alkalis and many acids. Weak against oxidizers at concentration and against chlorinated solvents.

Окно службы: About 0–80 °C.

Типичный отказ: Stress cracking, UV, concentrated bleach.

Preferred plastic head for oxidizers

PVDF

Fluorinated vinylidene polymer. Resists halogens, HCl, ferric chloride and industrial NaOCl. Hot concentrated NaOH attacks it.

Окно службы: About −20–120 °C. Caustic service much lower.

Типичный отказ: 50% NaOH near 25 °C is already a limit. Confirm concentration and temperature.

Diaphragm face, liner, seats, tape

PTFE

Near-inert fluoropolymer. Process chemicals see PTFE; the metal or elastomer behind it carries load. Not for elemental fluorine or molten alkali metals.

Окно службы: Process face often −20–150 °C. Limited by the backing, not the skin.

Типичный отказ: Cold flow (creep) without a backing diaphragm. ClO₂ can permeate a thin PTFE face.

Heads, plungers, clean-water hardware

SS316

Austenitic stainless with Mo for pitting resistance in mild chlorides. Passivated by nitric and aerated water. Reducing acids and free chlorine break the film.

Окно службы: Wide mechanically. Chloride SCC risk rises with heat.

Типичный отказ: Pitting, crevice corrosion and stress-corrosion cracking in NaOCl, HCl, FeCl₃. Do not specify 316 for bleach.

High-chloride metal head and plunger

Hastelloy C-276

Ni–Cr–Mo alloy. Holds mixed acids and chlorides that destroy 316. Default metal for seawater RO antiscalant and high-temp acid.

Окно службы: Process often −20–200 °C. Confirm the mix.

Типичный отказ: Few exceptions in water treatment. Still confirm oxidizing + reducing cocktails.

Valve balls, plunger coating

Ceramic (Al₂O₃)

Sintered alumina. Hard, chemically quiet in acids, bleach and coagulants. Hydrofluoric acid and strong thermal shock are the enemies.

Окно службы: Well above polymer heads. Limited by seats and body.

Типичный отказ: Chipping on impact. Viscous polymer can wet-seat and stick the ball.

O-rings, seats, diaphragm backing

FKM

Fluoroelastomer. Oils, many acids and NaOCl. Swells in ketones, amines and strong caustic.

Окно службы: About −20–200 °C in compatible media.

Типичный отказ: NaOH above ~5–15% is a common misspec. Use EPDM on caustic.

O-rings, backing, polymer service

EPDM

Ethylene-propylene rubber. Water, steam, dilute acid and caustic. Oils and oxidizers attack the unsaturation.

Окно службы: About −40–150 °C.

Типичный отказ: NaOCl is a life question, not a yes. Field failures are common — FKM or PTFE on bleach.

Peristaltic tube

Norprene

Thermoplastic elastomer tube. The tube is the wet-end: no seals, no valves. Acids, bases, food-grade options. Not a solvent hose.

Окно службы: About 0–80 °C. Fatigue, not melt, sets the interval.

Типичный отказ: Wall fatigue and abrasion. Plan a 6-month tube change on continuous duty.

Sanitary peristaltic tube

Silicone

Platinum-cured silicone. Clear, food and pharma. Poor against oxidizers, many acids and solvents.

Окно службы: Wide, but pump life is short at speed.

Типичный отказ: Swelling and tearing in bleach and strong acid. Use Norprene or PTFE tube instead.

Рабочие среды

Окно совместимости

5–13% available chlorine, ambient, off-gassing

Sodium hypochlorite

Off-gasses O₂ and Cl₂. Heat and metals accelerate decay. Auto-degassing heads (EM / DX) prevent vapour lock. Keep the tank cool and vented.

Типовая проточная часть

PVDF or PTFE-lined head · PTFE-faced diaphragm · ceramic or PTFE balls · FKM or PTFE seals. Not SS316.

Типы насосов под среду

ЭлектромагнитныеЦифровыеМоторные мембранные

Головки и металлы

PVCС ограничениями
PPС ограничениями
PVDFПредпочтительно
PTFEПредпочтительно
SS316Не применять
Hastelloy C-276Предпочтительно

Уплотнения, шары, шланги

PTFEПредпочтительно
FKMПредпочтительно
EPDMС ограничениями
Ceramic (Al₂O₃)Предпочтительно
NorpreneС ограничениями

Связанные модели

ПодборПодтвердить в КП