Manogauge manufactures direct-acting diaphragm pressure gauges designed for corrosive, viscous or hygiene-sensitive media where a conventional Bourdon tube would become blocked or damaged by process contact.
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ZX-05-1 · 0–60 kPa · ±1.6%
ZX-05-2 · 0–60 kPa · ±1.6%
ZX-04-R1 · 0–60 MPa · ±1.6%
ZX-04-R2 · 0–60 MPa · ±1.6%
ZX-01-R · 0–100 MPa · ±1.0 / 1.6%
A flexible diaphragm separates the process medium from the gauge movement. Pressure deflects the diaphragm, which transfers motion to the pointer via a linkage — keeping the medium fully isolated from the Bourdon tube and preventing blockage or corrosion of the measuring element.
Direct-acting diaphragm gauges in sizes 40–100 mm. Wetted parts in brass or stainless steel. Connection threads G, PT and NPT in 1/8 to 1/2 inch. Bottom or back connection. OEM dial artwork, custom ranges and special materials available on request.
Chemical and petrochemical dosing systems, food and beverage slurry lines, wastewater treatment, pulp and paper processes, pharmaceutical API handling and any medium that is viscous, crystallising, highly corrosive or hygiene-sensitive.
A Bourdon tube is a small-bore coiled tube: accurate, inexpensive and entirely unsuitable for anything that can settle, crystallise or solidify inside it. A diaphragm element replaces that narrow bore with a flat or corrugated disc clamped between two flanges, so the process sees a smooth, easily flushed face instead of a dead-ended tube. Three situations usually force the change. First, low pressure: below roughly 0.6 bar a Bourdon tube produces too little deflection for a readable scale, while a diaphragm still gives full pointer travel. Second, media that clog — slurries, latex, pigments, crystallising salts and fibrous liquids. Third, cleaning requirements, where a flush-mounted diaphragm can be wiped or CIP-cleaned and a Bourdon tube cannot. Where the medium is aggressive but clean and the pressure is high, a Bourdon gauge behind a diaphragm seal is often the better answer than a diaphragm element gauge, because it keeps Bourdon accuracy and range while still isolating the medium.
A diaphragm seal system is a closed, fill-fluid-filled volume between the diaphragm and the gauge. That fill fluid expands with temperature, and the expansion shows up as a reading error rather than as a fault. Two variables control how large the error becomes: the volume of fill fluid and the span of the gauge. A long capillary holds more fluid and therefore produces more temperature error, and a low-span gauge is affected proportionally more by the same absolute shift. As a practical rule, keep capillary length as short as the installation allows, prefer a direct-mounted seal over a capillary wherever the gauge can sit at the tapping, and question any low-range application that carries several metres of capillary. Fill fluid choice also matters: silicone oil is the general-purpose default, halocarbon fluids are used for oxygen service, and food-grade or FDA-listed fills are specified for food, beverage and pharmaceutical duty. State the process temperature, ambient temperature range and required span when requesting a seal assembly so the temperature effect can be estimated before manufacture.
Final configuration still depends on medium, temperature, pressure, connection and documentation requirements.
| Item | Common options | Selection note |
|---|---|---|
| Pressure range | Low pressure to 40 bar, depending on diaphragm type | Confirm normal pressure, pressure peaks and overpressure margin before selecting the capsule or diaphragm element. |
| Dial size | 40 / 60 / 80 / 100 mm | Larger dials improve readability on skid packages and elevated pipe runs. |
| Wetted material | Brass, 304 SS, 316L SS, PTFE-lined or special alloy by RFQ | Material must be checked against medium name, concentration and temperature. |
| Connection | G, PT, NPT, flange or sanitary-adjacent connection by model | Connection standard controls whether the gauge can be installed directly or needs an isolating seal. |
| Documentation | Calibration record, hydrostatic test record, material certificate by order scope | KS / EN837-1 documents are confirmed by applicable model and destination market. |
For a sodium hypochlorite dosing skid, the buyer should not select only by pressure range. The RFQ should state chemical concentration, normal pressure, pulsation from the metering pump, pipe material and whether crystallisation occurs during shutdown.
Use the RFQ form when you have range, connection, quantity or drawings. Use WhatsApp when you only need a quick compatibility check before preparing the full purchase file.
A diaphragm gauge uses a diaphragm sensing element for low pressure. A diaphragm seal isolates a standard gauge from the process medium through a sealed diaphragm assembly.
They can be configured for many corrosive media, but material and seal design must be checked against the exact medium, concentration and temperature.
Send medium, concentration, temperature, pressure range, connection standard, installation position, required material and quantity.
MOQ for standard diaphragm gauge models is typically 10–50 units. Special diaphragm materials or custom process connections may have higher minimums. Send your requirement for a confirmed MOQ.
Yes. Sample diaphragm gauges are available. Submit your specification via the RFQ form and note your sample requirement — our team will confirm availability and lead time.
Choose a diaphragm element for low pressure ranges where a Bourdon tube gives too little movement, and for media that would settle, crystallise or block a narrow tube — slurries, pigments, latex, fibrous or crystallising liquids. For clean but aggressive media at higher pressure, a Bourdon gauge fitted with a diaphragm seal usually gives better accuracy and range than a diaphragm element gauge.
The fill fluid between the diaphragm and the gauge expands with temperature and shifts the reading. The effect grows with fill volume and with lower gauge span, so long capillaries combined with low-range gauges are the worst case. Keep capillary length short, mount the seal directly where possible, and provide the process and ambient temperature range so the expected shift can be assessed before manufacture.
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