IP67 or IP68 for Pressure Transmitters? Choosing Ingress Protection for Outdoor and Wet Duty
Choose IP67 or IP68 from rain exposure, water depth and duration, cleaning and assembly conditions. Outdoor use does not automatically require IP68. Match the rating to the model, pressure type, connector and complete installation. Do not change the measurement reference simply to obtain a higher ingress rating.
What the IP code actually means
| Digit | Number | Meaning |
|---|---|---|
| First (solids) | 6 | Dust-tight, no ingress of dust |
| Second (water) | 7 | Protected against the effects of temporary immersion |
| Second (water) | 8 | Protected against continuous immersion, more severe than 7 |
The IP code follows the enclosure-protection classification in IEC 60529. Digit 7 concerns temporary immersion and 8 immersion under specified conditions. Obtain the product’s depth, duration and assembly requirements. Cleaning jets, hot water and chemicals need separate suitability checks; IP68 alone does not qualify those duties.
Why one model carries two ratings
A relative gauge device needs a vent path to atmosphere, which adds a structural route to the outside and makes sealing harder than for absolute or sealed gauge designs. The usual pattern is:
| Pressure type | Configuration example (not a universal rule) | Structural reason |
|---|---|---|
| Absolute | IP68 | Reference cavity is a sealed vacuum; no venting needed |
| Sealed gauge | IP68 | Reference pressure sealed inside; no venting needed |
| Relative gauge | IP67 | Must communicate with atmosphere, adding a sealing path |
PM160-E distinguishes gauge IP67 from absolute/sealed-gauge IP68. WA30 also specifies an M12 waterproof cable for its applicable IP68 versions. These are configuration-specific statements, not ratings for other models or arbitrary connectors.
The leak is rarely the housing
Sealing the enclosure is not the hard part. In long service, water usually enters at one of three places:
- Buttons and controls: check the sealing design and complete-assembly test evidence. A physical button is not automatically a leak path.
- Cable entry: inspect jacket, gland and end treatment. An unsuitable cable or seal can allow water to travel along conductors. Watertightness depends on the complete cable assembly; not all cables are inherently non-watertight.
- The process seal — a gasket material mismatched to temperature ages and fails.
WA30 display versions use an integrated magnetic switch that separates actuation from the internal electronics and avoids a conventional through-panel button opening. This reduces the associated button-seal leakage path. Long-term protection still depends on seals, connectors, assembly and environment; the switch does not guarantee IP68 throughout service life. Confirm the complete configuration and installation conditions.
Thermal cycling: the test that gets skipped
A static immersion test does not establish long-term reliability. Separately assess temperature cycling, seal ageing and cable strain. Request the relevant test method and report and consider retesting the final assembly. Do not claim a verified thermal-cycle count without the corresponding evidence.
Specifying by application
| Application | Recommended rating | Associated requirements |
|---|---|---|
| Indoor cabinet, dry workshop | IP65 to IP67 | Confirm dust, cleaning and installation requirements |
| Outdoor equipment, exposed to rain | By actual exposure | Cable outlet facing down; seal the connector |
| Fire mains, pump rooms, below grade | Check IP68 conditions if immersion is possible | Retain required pressure reference; confirm venting, connector and assembly |
| Submersible equipment, continuous immersion | IP68 | Confirm depth, water quality, duration and complete assembly; not unlimited immersion |
Checklist
- Pressure type: confirm whether local-atmosphere reference is required. Protection must be compatible with that reference; do not substitute another type solely for its IP rating.
- Confirm the connector — whether a waterproof type such as M12 is used and how the cable outlet is treated.
- Confirm whether there is a button — prefer magnetic or buttonless designs for display units.
- Seals: confirm the temperature range, medium compatibility and assembly conditions for the actual compound. NBR or FKM names do not establish one universal temperature rating.
- Confirm the verification method — whether waterproof retesting after thermal cycling was performed.
Next step
Compare WA30 display/magnetic-switch options for local inspection, PM350-RTU communications and power for distributed reporting, and PM160-E for industrial measurement. Check reference, range, ingress configuration and environment for each. An IP68 label alone does not qualify a device for any underwater duty.
More answers in the FAQ.
Related documentation: RS WA30 outdoor transmitter · RS PM350-RTU wireless terminal · RS PM160-E · downloads page
Specifications: View WA30 datasheet (PDF) · Download PDF · View PM160-E datasheet (PDF) · Download PDF