Compact Absolute Pressure Transmitter with Miniature Thread Mount for OEM Systems

Skid builders and machine manufacturers do not have spare panel space, and they do not want a pressure instrument that needs a technician to re-zero it every time the weather changes. The QWY-322 packs a vacuum-referenced absolute pressure measurement into a body about the size of a finger, with a 4-20 mA or RS485 output that drops straight into a PLC. Because the reference is a sealed vacuum, every unit you ship reads the same in Denver, Dubai or Dusseldorf - no altitude correction, no barometric trim, no vent line to design into your manifold. It is the absolute pressure transmitter built for OEM volumes, OEM lead times and OEM budgets.

Why Do You Need Absolute Pressure Measurement in Compact and OEM Applications?

OEM equipment travels. A compressor package built in one country runs at altitude in another; a leak test rig changes floors in the same factory; a vacuum packaging machine works differently on a stormy day unless the measurement ignores the weather. If your machine references atmospheric pressure, its performance changes with the site, and your customer blames your equipment for a problem caused by the barometer. Absolute pressure measurement removes that variable from your product entirely. There is a second, quieter reason: gauge transmitters need an atmospheric vent, and in compact OEM designs that vent is exactly where dirt, water and paint end up. A sealed vacuum reference has no vent, no filter, no maintenance item. For equipment that must perform identically everywhere, absolute measurement is the engineering shortcut to consistency.

Working Principle: Miniature Sensor, Sealed Vacuum Reference, Smart Output

The QWY-322 uses a micro-machined diffused silicon cell in which one side of the diaphragm is exposed to process pressure and the other side is sealed against a vacuum reference during manufacturing. The resulting signal is inherently absolute - it needs no atmospheric compensation at all. An integrated ASIC amplifies, linearizes and temperature-compensates the signal, and the output stage delivers a choice of 4-20 mA, 0-5 V or RS485 Modbus to match your control architecture. The whole assembly is welded into a 316L body with a G1/4 or 1/4 NPT thread, small enough to mount directly on a manifold, a valve block or a test fixture. Because there is no separate reference tube or vent port, installation is one thread and one connector - which is exactly what OEM assembly lines need.

Structural Advantages of the QWY-322 Compact Absolute Pressure Transmitter

• Ultra-compact body of approximately 27 x 85 mm, weighing under 150 g for space-constrained skids
• Sealed vacuum reference with no vent port, no filter and no altitude correction in software
• Wide 9-28 V DC power supply range compatible with battery and 24 V systems
• 4-20 mA, 0-5 V and RS485 Modbus output options for any PLC or controller
• All-welded 316L construction with IP67 protection for washdown and outdoor duty
• ASIC temperature compensation from -20 to 100°C media temperature
• G1/4, 1/4 NPT and M20 x 1.5 threads with custom variants for OEM manifolds
• OEM customization: your logo, cable length, connector type, range and tag marking

Pain Point Analysis: 4 Working Conditions Where Absolute Reference Wins

Application Case 1: Vacuum Leak Test Rigs for EV Battery Housings

Application Case 2: Nitrogen Generator Skids for Container Shipping

Eight Product Advantages of the QWY-322

1. Miniature size and light weight for direct mounting on manifolds, valve blocks and fixtures
2. True absolute measurement with sealed vacuum reference - no vent, no altitude error, no site trim
3. Three output options (4-20 mA, 0-5 V, RS485 Modbus) for any control architecture
4. Wide 9-28 V DC supply for battery-powered and mobile equipment
5. All-welded 316L construction with IP67 rating for harsh OEM environments
6. ASIC compensation ensures unit-to-unit consistency for volume production
7. OEM branding, cable, connector and range customization with stable lead times
8. 18-month warranty and batch traceability for OEM quality records

Technical Parameters

Why Choose Our Absolute Pressure Transmitter?

Qinwei Instruments has supplied compact pressure instruments to OEM customers in packaging, gas, compressor and test equipment industries for over a decade. For OEM buyers, the difference is in the details: batch-to-batch consistency from ASIC-based compensation, documentation that matches your incoming inspection, and customization - logo, connector, cable, range and label - without minimum-order pain. Our factory performs a 100% pressure and temperature test on every unit, and we keep safety stock of the most common OEM variants so your line never waits. Tell us your annual volume and your specification, and we will qualify samples against your test procedure before you commit to volume.

SEO FAQ

Because gauge sensors measure pressure relative to the local atmosphere, and the atmosphere is different at every site. At 1,000 meters altitude, atmospheric pressure is roughly 12 kPa lower than at sea level, so a gauge sensor on a vacuum packaging machine or leak tester reports a different baseline in every city. If your machine control logic was tuned at your factory, it will be slightly wrong at your customer's site - and the customer blames the machine. An absolute pressure transmitter measures against a sealed vacuum reference, so the reading is the same everywhere. For OEM equipment, absolute measurement converts a site-dependent product into a consistent product, which is why more equipment builders specify it every year.

Yes. As a manufacturer, we support full OEM customization: your logo on the housing and label, your preferred electrical connector (M12, DIN, cable pigtail, custom pinout), your cable length, your pressure range, your output signal and your tag format. Custom ranges and special calibration points are configured at the factory, so the unit arrives ready to install with no field programming. We recommend starting with a sample qualification against your test procedure; once the sample is approved, we lock the specification and hold it for your volume orders. Minimum order quantities for customized variants are modest, and standard variants are available from stock.

For analog PLC inputs, 4-20 mA is the most robust choice because the current loop is immune to voltage drop over cable length and gives you a live-zero diagnostic (a broken wire reads below 4 mA). For digital systems, RS485 Modbus RTU provides the pressure value, diagnostics and configuration registers over a single twisted pair, ideal for multi-drop networks of several transmitters. The 0-5 V output suits battery-powered and low-cost analog inputs, but it is more sensitive to supply voltage variation and cable resistance. If your machine uses a mix of signal types, we can supply the QWY-322 in matched batches with the same output so your assembly line does not need to handle multiple variants.

Every sensing cell is individually temperature compensated by the ASIC at three temperature points, and each finished transmitter is 100% tested for zero, span, linearity and hysteresis against a reference standard. For volume OEM orders, we additionally test sample units from each production batch against your approved sample and keep the records for traceability. The all-welded construction removes the assembly variability that comes from glued or O-ring sealed sensors. In practice, our OEM customers report that they can install the QWY-322 without per-unit recalibration, which is the consistency standard we hold ourselves to.

The vacuum reference is sealed during sensor manufacturing by laser welding, and there is no vent, valve or pump involved, so there is nothing to wear or leak over the instrument's life. The dominant aging mechanism is slow diaphragm drift, specified at less than ±0.1% FS per year, which is negligible for most OEM applications such as leak testing, blanketing and machine monitoring. For equipment with a 10-year design life, we recommend a calibration check at the 5-year major service interval, and we provide the calibration procedure in the documentation package. The 18-month warranty covers the transmitter, and the modular design allows factory repair rather than whole-unit replacement if a unit is ever damaged.

Yes. The all-welded 316L body has no internal tubes or loose parts, and the IP67 rating protects the electronics against hose-down, dust and temporary immersion, which covers most machine-building environments. The electronics are potted to resist vibration and moisture, and the unit has been validated for the vibration levels typical of compressor packages and automated machinery. For extreme vibration, we recommend mounting the transmitter with a short rigid connection or a vibration damper and keeping the cable mechanically supported. If your application has unusual shock or vibration requirements, send us the test specification and we will qualify the unit against it before you order in volume.