Choosing a Pressure Transmitter for Fire and Water Networks: IP68, Water Hammer and Local Display
For fire and water networks, check pressure reference, range and transients, installation protection, measurement error and local readout needs together. RS-WA30 offers display and magnetic-switch options for inspection points. IP68 and overload figures are conditional specifications, not unlimited immersion or unconditional protection against water hammer.
Three checks for outdoor points
| Failure mode | Mechanism | How to specify against it |
|---|---|---|
| Water ingress | Seepage under continuous pressure at the cable entry, button gap or connector seal | Verify the assembled unit for exposure conditions, including connector and controls |
| Water hammer damage | Pump start/stop and fast valve closure produce spikes several times the working pressure | Check range-specific overload and repeated pulses; validate snubbing where needed |
| No readable value | No local display, so fault-finding means disconnecting and metering | Fit a local OLED display readable at a glance during rounds |
Assess enclosure protection, mechanical limits and measurement error together. Sealing, connector assembly, medium and maintenance also affect field performance; an accuracy figure or IP code alone does not establish service life.
What it takes to make IP68 real
Read IP68 with the specified depth, duration and complete assembled configuration. Buttons, cable entries and connectors all need sealing verification. A physical button is not inherently a leak, and a magnetic switch does not replace complete-product ingress testing.
The RS-WA30 display version uses an integrated magnetic switch: the mechanical actuator is physically isolated from the internal circuitry, which removes the button penetration altogether. On the power-saving version, one press lights the screen for 15 seconds before it switches off again (duration customisable); a permanently-on version is also available.
The rating still depends on pressure type: absolute and sealed gauge versions reach IP68 with an M12 waterproof cable, while the gauge version body is IP67. That is tied to the connector choice — the model name alone does not decide it.
Water hammer: reading the overload table
| Range (bar) | Overload (bar) | Overload factor | Burst (bar) |
|---|---|---|---|
| 1 | 10 | 10 × | 50 |
| 2 | 10 | 5 × | 50 |
| 5 | 25 | 5 × | 50 |
| 10 | 50 | 5 × | 300 |
| 20 | 100 | 5 × | 300 |
| 30 | 150 | 5 × | 300 |
The table gives range-specific overload and burst figures under datasheet conditions. Burst pressure is not allowable operating pressure. Repeated water hammer also involves pulse duration, frequency and fatigue. For an illustrative 6 bar operating pressure and 20 bar peak, the 0–10 bar version has a 50 bar overload figure; transient suitability still needs verification.
RS WA30 response is as fast as 0.5 ms. This is sensor response, not the display, PLC or logger’s peak-capture rate. Stability ≤0.10 %FS/year and >10×10⁶ cycles at 10–90 %FS also do not directly establish field service life.
What the local display shows
The display version uses an OLED screen showing pressure and temperature: display accuracy ±0.2 % (-20 °C to 85 °C, excluding the sensor output itself), with temperature display accurate to ≤±2 °C. Note that display accuracy and measurement accuracy are different things — the first describes how faithfully the screen reproduces the value.
Supply and output vary by sub-model, so confirm them together:
| Check | What to confirm |
|---|---|
| Output version | 4–20 mA, 0.5–4.5 V and RS485 versions; confirm the ordered protocol, custom I²C option and connector |
| Supply and load | Use the selected sub-model’s electrical table and wiring drawing; do not mix display and cable variants |
| Display power | Distinguish always-on and power-saving versions in the complete budget |
| Surge protection | Check port, test method and site protection; product ratings do not replace system surge protection |
The surge rating deserves its own look: 2 kV on the display version, 500 V line-to-line and 1 kV line-to-earth on the cable version. For overhead runs or lightning-prone areas, check this against the site’s surge protection design. I²C digital output is available on request.
Accuracy terms: TEB and altitude
The RS-WA30 Total Error Band is ≤±0.50 % FS over -20 °C to 85 °C. Two qualification conditions belong in the technical agreement:
Installation and materials
For remote reporting, connect WA30 to acquisition equipment compatible with its output, or assess the integrated RS PM350-RTU terminal. WA30 itself is not a wireless terminal, but local display and remote monitoring can be combined at system level.
FAQ
Does every version reach IP68?
No. Absolute and sealed gauge versions with an M12 waterproof cable reach IP68; the gauge version body is IP67. Confirm pressure type and connector together.
How is the screen switched on, and does it drain power?
By the integrated magnetic switch. On the power-saving version one press lights the screen for 15 seconds (customisable) before it switches back off; a permanently-on version is available where that is needed.
Does high altitude change accuracy?
Yes. TEB of ≤±0.50 % FS is measured at 0-100 m altitude; above 100 m, on-site adjustment with the Rodee service tool is required.
How do I choose a range that survives water hammer?
Check the selected range’s overload figure, then assess repeated pulses, duration and any snubber requirement. The 0–10 bar version lists 50 bar overload and 300 bar burst, but static figures alone do not guarantee survival of repeated water hammer.
Can zero be adjusted on site?
Yes. Field-programmable zero adjustment is supported across the series, using the Rodee zero programming tool set (sold separately).
More answers in the FAQ.
Related documentation: RS-WA30 outdoor pressure transmitter with digital display
Specifications: View WA30 datasheet (PDF) · Download PDF
Related products and documentation: downloads page