Chemical Rotameter Flow Meter

Match material to medium first, then size the meter. PTFE-lining covers the broadest acid and alkali set; hydrochloric acid (HCl) at any concentration, sulfuric acid (H₂SO₄) below 80 %, sodium hydroxide (NaOH) up to 50 %, chloride brines, and most chlorinated solvents. Hastelloy C handles chlorine gas, wet chlorine, mixed acids, and oxidizing service where PTFE would creep under pressure or temperature. Titanium handles chloride-rich liquids and seawater where stainless pits and Hastelloy is over-spec. Monel is the material for hydrofluoric acid (HF) and fluoride salts; PTFE creeps under fluorine load and Hastelloy is attacked. Hastelloy B is for hot reducing acids where Hastelloy C falls short. No single material covers everything; the order entry sheet asks for medium, concentration, temperature, and pressure so the application engineer can verify the build before quotation.

Two reasons. First, the corrosive atmosphere around an acid or chlorine line attacks electronics; HCl vapor, chlorine, and sulfur fumes pit transmitter housings, etch connector pins, and shorten cable life. The passive pointer has nothing to corrode beyond the wetted body itself. Second, the pointer build has no electronics inside the meter, so no Ex certificate is required; for a Zone 1 chlor-alkali bay or a pickling line in a hazardous area, the pointer is Ex-by-design at zero cert overhead. The 4-20 mA / HART option is available when the buyer needs remote readout, but it adds Ex d IIC T6 Gb housing cost, an extra failure surface, and dedicated wiring; choose it only when a control-room readout is required.

PTFE-lined builds carry tighter pressure and temperature limits than the bare-alloy versions. Maximum medium temperature on the PTFE liner is +85 °C; above that the liner softens and creeps under pressure. Maximum working pressure on the PTFE-lined build is 1.0 MPa, regardless of what the flange class allows; the liner is the limit, not the flange. For higher pressure or higher temperature on chemical service, go to a bare-alloy build: Hastelloy C, Titanium, or Monel covers the same acids at −40 to +120 °C and up to 2.5 MPa (DN15 to DN50) or 1.6 MPa (DN65+). Send the medium composition, concentration, and operating P / T to engineering and the application team will confirm the material that stays inside its corrosion and mechanical limits.

The variable-area principle is gravity-driven. The float weight sets the reference force; upward flow drag lifts the float against gravity until the two balance, and the equilibrium height reads as flow on the printed scale. Horizontal mount removes the gravity reference and the float will not return to a repeatable zero. The factory build is fixed on vertical / flow bottom-up; meter body within ±2° of true vertical. A horizontal-mount version exists as a separate factory order code with a different float and spring assist, but it is not a field-convert. On chemical service the vertical mount also helps prevent acid puddling at the lower flange and gas pocketing at the upper flange; the line stays self-draining.

Standard lead time is 5 to 7 business days from order confirmation, factory direct. Each meter ships with an ISO 9001 calibration certificate listing the DN, float class, calibrated medium reference, and tested flow range; the mill certificate for the chosen wetted material (PTFE liner thickness, Hastelloy C heat number, Titanium grade, or Monel grade); the build-coded serial plate with the model string; and the installation drawing showing flange dimensions, total length, and the vertical-mount orientation. Electrical builds add the Ex d IIC T6 Gb certificate and the 4-20 mA / HART loop-test record. Hazardous-area passive builds carry no Ex certificate because there are no electronics in the meter to certify.

Route conductive clean acid (conductivity above 5 microsiemens per cm) to a PFA-lined electromagnetic meter; the magflow is electronic but holds tight accuracy across a wider turndown for control-loop service. Route slurry, particulate-laden, or two-phase corrosive service to magflow with abrasion-resistant liner; the rotameter float clearance jams under solids. Route high-viscosity corrosives above 5 cP (concentrated phosphoric, viscous polymer additive) to the Coriolis straight-tube family; the rotameter float calibration is valid only for clean low-viscosity media. Route custody / fiscal billing service to Coriolis or electromagnetic; the rotameter is indication-grade at ±1.5 % of full scale, not billing-grade. Route sub-DN15 lab service to the low-flow rotameter counterpart.