Image note: The representative photograph shows an industrial luminaire, not a pressure switch. It does not illustrate pressure-switch construction or approval.
Explosion-proof pressure switches: organise the enquiry
The questions below are an editorial purchasing aid. They are not evidence that a particular model is certified, available from MMAIATEX or suitable for a specific installation. Use the supplier's current documents and the project's competent reviewers to resolve the actual selection.
| Enquiry area | Information to identify | Decision it supports |
|---|---|---|
| Process duty | Medium, pressure conditions and required switching behaviour | Whether the proposal addresses the process need |
| Electrical interface | Output type, circuit requirements and load information | Whether the proposed interface matches the design |
| Hazardous-area evidence | Exact model, marking, documents and application conditions | Whether the Ex proposal can proceed to review |
| Supplied configuration | Ordering reference, options and document revisions | Whether the quotation describes the reviewed item |
1. What does a pressure switch do?
A pressure switch changes a switching output in response to pressure reaching a specified condition. It is not necessarily a continuous pressure measurement output. WIKA's electronic pressure-switch explanation distinguishes switching signals from additional analogue or display functions available on some designs. In an enquiry, specify whether the project needs a switching signal, a measured value, or both. Do not assume that every device offers all three functions.
2. Does explosion-proof mean pressure-proof?
No. Explosion-protection documentation does not by itself establish suitability for the process pressure. IEC 60079-0:2026 addresses general construction, testing and marking of Ex equipment and components. The process-pressure limits and conditions of the actual instrument still need separate identification. Ask which documents cover those conditions. Do not treat a pressure rating for a connection, an enclosure description and an Ex marking as interchangeable evidence.
3. What pressure information should an enquiry include?
Describe the intended duty and provide the project's defined pressure conditions, units and pressure reference. Identify the required switching condition and any stated abnormal conditions for review. If an input is not yet established, mark it as unresolved instead of selecting a convenient catalogue value. Ask the supplier to distinguish the offered measurement or adjustment range from other pressure limits shown in its documentation. This FAQ supplies no universal pressure threshold.
4. Are the switching point and reset point the same?
Not necessarily. Electronic pressure-switch designs can distinguish the condition at which an output changes from the condition at which it resets. The WIKA explanation above describes these as separate settings on relevant designs. For procurement, state the required behaviour and ask how the proposed device documents it. Do not assume independent adjustment is available on every model. Any final settings belong to the approved engineering and commissioning process, not this article.
5. Can any switch output operate the intended circuit?
No universal compatibility should be assumed. Give the reviewer the proposed output type and the actual receiving-circuit or load requirements. Ask for the manufacturer's applicable electrical ratings and connection documentation. A short description such as switch output leaves important questions unanswered. For contact terminology, use the separate NO and NC contact-numbering guide; numbering alone does not approve a circuit or its load.
6. Does IEC 60947-5-1 establish Ex approval?
No. The current IEC 60947-5-1:2024 catalogue record identifies Edition 5.0 and a scope concerning control-circuit devices and switching elements. That is a different evidence question from explosion protection. Ask which standards and documents apply to the actual offered device. Citing a control-device standard in a quotation does not, by itself, establish a hazardous-area approval or confirm a particular pressure-switch configuration.
7. What should be checked about the process connection?
Identify the proposed connection, the process medium and the manufacturer's stated material and service limitations. Have the responsible reviewer resolve compatibility rather than assuming that a matching thread description completes selection. Where a process-sealing question arises, the separate IEC TS 60079-40 process-seal scope guide explains that subject. Do not infer a sealing arrangement, approved adapter or protection boundary from the outside appearance of a device.
8. What Ex documents should the buyer request?
Request the exact offered model designation, proposed marking, relevant conformity or certificate references, instructions and any conditions applying to that configuration. The appropriate package depends on the product and destination requirements. Where an IECEx certificate is claimed, the IECEx equipment-scheme FAQ identifies its online record as the controlled version for checking current status. A brochure or an old downloaded copy is not a substitute for that check.
9. Can a photograph confirm the protection method?
No. A photograph can help identify an item, but it cannot establish the scope of its certification or the complete construction behind its protection method. Use the marking and corresponding documents. The representative website product photograph accompanying this article is not an illustration of an approved pressure-switch configuration. It must not be used to select a model, pressure rating, electrical interface or hazardous-area application.
10. Can a matching replacement be ordered by appearance?
Not safely on appearance alone. Give the reviewer the existing identity and documentation alongside the proposed replacement's complete ordering reference. Record any differences in output, connection, options or document revision. A similar-looking replacement still needs an identifiable review outcome. If information is missing, keep the substitution unresolved. This is a purchasing-record recommendation, not permission to remove, open or replace installed equipment.
11. Does Ex certification prove shutdown reliability?
No. Explosion protection and the performance required of a safety-related function are separate review subjects. The SIL versus explosion-proof certification guide discusses that boundary. If the project assigns a shutdown or protective duty, involve the responsible functional-safety reviewer and identify the evidence the design requires. Do not assign a safety integrity claim to a pressure switch merely because its Ex documentation is available.
12. Who resolves installation and commissioning questions?
The responsible competent personnel must resolve them using the applicable project requirements and manufacturer documentation. IEC 60079-14:2024 addresses Ex electrical installation design, selection, installation and initial inspection, including documentation and competence. These procurement questions do not replace that process. Do not derive wiring, adjustment, isolation or pressure-testing instructions from this FAQ or from the representative photograph.
Current MMAIATEX certification status
MMAIATEX is the public brand of MMAIATEX Explosion-proof Technology (Zhejiang) Co., Ltd. On the review date, its About page describes ATEX, IECEx and CCC certification as in progress. This is an attributed website statement, not independent confirmation of a model's certificate. Verify exact model marking, certificate scope and current documentation. This article announces no pressure-switch product or certification.
Safety and legal disclaimer
This is general purchasing information, not a pressure-system design, installation procedure, safety-function assessment or legal opinion. Source links explain limited concepts or publication scopes; they do not certify the proposed equipment. Hazardous-area and pressurised-system work requires the applicable competent process and safety arrangements.
Contact MMAIATEX about a documentation enquiry
Provide the proposed equipment reference, destination market and the specific documentation question. Identify any unresolved process or electrical requirements so the scope of the enquiry is clear. Contact MMAIATEX.