Factory-direct pressure switches and transmitters built for OEM equipment builders worldwide. Mechanical pressure switches, vacuum switches, and 4-20 mA pressure transmitters — all CE certified, IP67 rated, customizable to your exact specification.
SEGMENsensor manufactures three pressure product lines for OEM equipment: 4-20 mA pressure transmitters from 0–0.1 to 0–400 bar, the SYK102 mechanical pressure switch adjustable from 0.5 to 8.5 bar, and vacuum pressure switches for -1 to 0 bar. A switch gives an on/off signal at a set point; a transmitter gives a continuous signal.
Pressure switch or pressure transmitter, and how to wire each one to a PLC. Both sense the same pressure. A switch has a set point: above it, the contact switches on. It switches off again only at a lower reset point. That gap is the hysteresis. A transmitter sends a continuous 4–20 mA signal that follows the pressure. Wiring a switch is simple: the relay contact connects 24 V to a digital input of the PLC. When pressure passes the set point, the contact closes and the input turns on. Below the reset point, it turns off again. A transmitter uses a current loop. The supply, the transmitter and the PLC input sit in one series circuit. Connect the supply positive to the transmitter, and its return to the PLC analog input. One pair of wires carries both power and signal. Keep the total loop resistance within 600 Ω at 24 V. The PLC converts the current to pressure: 4 mA is zero, 20 mA is the full range. Because zero pressure reads 4 mA, a reading of 0 mA means a broken wire, not zero pressure. Which one? Use a switch for a simple trip, an alarm or a pump cut-out. It even works without a PLC. Use a transmitter when a PLC must read, log or control the actual pressure value. The SYK102 switch adjusts from 0.5 to 8.5 bar, with an SPDT contact rated 16 A / 250 V AC. Pressure transmitters cover 0–0.1 bar up to 0–400 bar, at ±0.25% FS. Vacuum switches are also available, with NPN, PNP, relay or IO-Link output. SEGMENsensor pressure switches and transmitters. OEM volume supply. Quotes at segmensensor.com.
Pressure switch or pressure transmitter: which one do you need? Both sense the same pressure. The difference is what they send out. A pressure switch has a set point. When pressure rises past it, the contact switches on. It switches off again only at a lower reset point. That gap, the hysteresis, stops it from chattering. A pressure transmitter sends a continuous 4–20 mA signal that follows the pressure, so the PLC always knows the exact value. Use a switch for simple pump control and alarms. Use a transmitter for monitoring, control loops and trends. SEGMENsensor makes both: the SYK102 switch, and transmitters up to 400 bar. Learn more at segmensensor.com.
psi, psig, psia: what is the difference? Pressure is always measured from a reference. Absolute zero is a perfect vacuum. At sea level, the atmosphere adds about 14.7 psi. Absolute pressure, psia, is measured from the vacuum. This process sits at 34.7 psia. Gauge pressure, psig, is measured from the air around the sensor. The same process reads 20 psig. Below atmosphere, gauge pressure turns negative. −10 psig is 4.7 psia. Use gauge for most tanks and hydraulic systems, and absolute for vacuum or sealed processes. 1 bar = 14.5 psi. SEGMENsensor pressure transmitters: gauge, absolute and differential. Try our unit converter at segmensensor.com.
4–20 mA: why is it everywhere? A 4–20 mA transmitter, its power supply and the PLC input form one series loop. The same current flows through every part of it. The current represents the measured value. 4 mA is the bottom of the range, 20 mA is full scale. Here, 0–10 bar. The formula: I = 4 + 16 × value ÷ span. At 6 bar, that is 13.6 mA. Why start at 4? A live zero shows a broken wire as 0 mA, it can power a 2-wire transmitter, and cable resistance does not change the signal. In the PLC, a 250 Ω resistor turns 4–20 mA into 1–5 V. SEGMENsensor pressure transmitters with 4–20 mA output. Try our calculator at segmensensor.com.
Every unit is tested before shipment. Photos from our own production and test lines.
Close-up photos of a standard build. Process connection, range, output and connector options are listed in the specifications.
Pressure measurement for mining in South Africa, oil sands in Canada or private label in India: see our export market pages.
What are pressure switches and pressure transmitters? A pressure switch outputs a discrete relay or transistor signal when fluid pressure crosses a user-set threshold — used in safety cut-outs, pump control, and alarm circuits. A pressure transmitter outputs a continuous 4-20 mA or 0-10 V analog signal proportional to pressure — used in PLC monitoring and closed-loop control systems. SEGMENsensor manufactures both types as a direct factory supplier in Shenzhen, China, with CE, IP67, and ATEX certification available. Pressure range: 0.1 bar to 400 bar. OEM volume supply. Production lead time: confirmed with the quotation.
Full comparison with output diagram and selection steps: pressure switch vs pressure transmitter. For the definition, sensing-cell types and datasheet terms, see what a pressure transducer is.
Mechanical pressure switches, vacuum switches, and 4-20 mA transmitters — engineered for HVAC, refrigeration, hydraulics, chemical, and process industries.
Adjustable mechanical pressure switch with SPDT relay contact. Set point adjustable via graduated dial. Suited for pumps, compressors, HVAC systems, and general process control. Brass or stainless steel process connection available.
Electronic and mechanical vacuum pressure switches for vacuum packaging, semiconductor wafer handling, medical suction equipment, and refrigeration recovery. Adjustable set point with LED status indicator. Optional IO-Link output for Industry 4.0 integration.
Piezoresistive and ceramic membrane pressure transmitters with 2-wire 4-20 mA output. Available in gauge, absolute, and differential configurations (gauge vs absolute vs sealed gauge explained; accuracy classes in % FS vs % of reading explained). Process connections: G1/4, G1/2, 1/4 NPT, 1/2 NPT. Stainless steel wetted parts, optional ATEX for hazardous areas.
Datasheets, CE declarations, and product brochures — no registration required.
OEM pressure switch manufacturer China. All parameters configurable for your application. Request a custom spec sheet for non-standard ranges.
| Parameter | SYK102 Pressure Switch | Vacuum Pressure Switch | 4-20 mA Pressure Transmitter |
|---|---|---|---|
| Pressure Range | 0.5 – 8.5 bar (adjustable) | -1 – 0 bar (vacuum) | 0–0.1 bar to 0–400 bar (selectable) |
| Output Signal | SPDT relay, 16 A / 250 VAC | NPN / PNP / Relay / IO-Link | 4-20 mA (2-wire) / 0-10 V / RS485 |
| Accuracy | Mechanical set point ±2% | ±2% FS | ±0.25% FS (standard) / ±0.1% FS (hi-acc) |
| Sensing Principle | Bellows / bourdon tube | Piezoresistive silicon / ceramic | Piezoresistive silicon / ceramic membrane |
| Process Connection | G1/4 Male (standard) / 1/4 NPT | G1/4 / 1/4 NPT / custom | G1/4, G1/2, 1/4 NPT, 1/2 NPT, flush diaphragm |
| Wetted Materials | Brass / 316L SS (on request) | 316L SS / PVDF (corrosive media) | 316L SS / Hastelloy / ceramic (food grade) |
| Electrical Connection | Cable gland PG9 / terminal | M12 × 1 connector / cable | 2-wire loop powered / M12 connector |
| Supply Voltage | AC 250 V (relay contact) | 10–30 V DC | 10–36 V DC (loop powered) |
| Operating Temperature (media) | -20°C to +80°C | -20°C to +80°C | -40°C to +125°C |
| Operating Temperature (ambient) | -20°C to +70°C | -20°C to +70°C | -20°C to +85°C |
| Overload Pressure | 1.5× rated range | 2× rated range | 2–5× rated range |
| Protection Rating | IP65 (IP67 option) | IP67 | IP68 (1.5 m continuous) |
| Certifications | CE RoHS | CE RoHS UL | CE RoHS ATEX (option) |
| Samples | 1–5 pcs, 5–7 working days | 1–5 pcs, 5–7 working days | 1–5 pcs, 5–7 working days |
| Standard Lead Time | Confirmed with the quotation | Confirmed with the quotation | Confirmed with the quotation |
Ranges 0–0.1 to 0–400 bar, accuracy classes ±0.25% FS and ±0.1% FS, output options, process connections, wetted materials, temperature limits, IP rating, dimensions and the ordering code. No registration required.
Understanding the operating principle helps select the right device for your OEM application. SEGMENsensor engineers are available to assist with application-specific selection.
Process pressure acts on a bourdon tube, bellows (mechanical switch) or a silicon/ceramic diaphragm (electronic transmitter). The diaphragm deflects proportionally to applied pressure.
Mechanical switches convert diaphragm movement to a relay contact action. Electronic transmitters use piezoresistive strain gauges in a Wheatstone bridge — resistance change is converted to a 4-20 mA current signal by an ASIC conditioner.
Pressure switches send ON/OFF to a PLC digital input or relay coil. Transmitters send a continuous 4-20 mA loop current to a PLC analog input card — the PLC calculates pressure from the 4–20 mA range mapping.
Choose a pressure switch when you need simple on/off control (pump start/stop, safety cut-out). Choose a pressure transmitter when you need a continuous reading for data logging, PI control loops, or multi-point display.
SEGMENsensor supplies OEM pressure switches and transmitters to equipment builders across HVAC, refrigeration, industrial process, and hydraulic sectors. Custom set points, housing, and certification available for each application.
Since 2019, SEGMENsensor has supplied pressure switches and transmitters to OEM equipment builders across 30+ countries. We are a direct manufacturer — no trading company in between — with in-house engineering, tooling, and calibration capabilities.
Production in our Shenzhen factory, OEM volume supply, samples 1–5 pcs in 5–7 working days, production lead time confirmed with the quotation, reply within 24 hours on working days.
SEGMENsensor holds all required certifications for global OEM equipment builders. Documentation shipped with every order — no extra charge, no registration required.
Full quality management system. Controlled production, inspection records, and traceability on every batch.
Electromagnetic compatibility and low-voltage directive. CE declaration provided for EU customs clearance.
Explosion-proof versions available as an option for Zone 1/2 hazardous areas. Ex marking as stated on the certificate of the specified model.
All standard models are RoHS compliant. RoHS declaration of conformity provided on request.
UK Conformity Assessed — required for Great Britain market entry. Equivalent to CE for England, Scotland and Wales.
UL certification applies to select pressure switch and transmitter models only — ask us which models carry it before you specify for North America.
Shenzhen, Guangdong, China · Registration No. 91440300MAEUXXQU04
info@segmensensor.com · +86 138 2870 4591 · www.segmensensor.com
Choosing a range and output? Read the 4-20 mA pressure transmitter selection guide, or see our pressure transducer supplier for Australia page for export terms.
Common questions from OEM engineers and procurement teams. Can't find your answer? Email info@segmensensor.com — we reply within 24 hours.
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Pressure unit converter (psig / psia / bar) · 4–20 mA calculator
Tell us your pressure range, output type, process connection, and quantity. Our engineering team replies within 24 hours — no bot, no call centre.
SEGMEN (Shenzhen) Industrial Development Co., Ltd. · Shenzhen, China · info@segmensensor.com · +86 138 2870 4591
Pressure sensing is often paired with flow and level monitoring. SEGMENsensor manufactures all three in-house.