Test Certificate


Thread Starter

anand s

Dear all

Could anyone explain what is "Simple Apparatus Test Certificate"?

What is the certificate applicable for Process switches like Pressure, level, flow and temperature switches coming Hazardous area say fuel oil area like HSD, Naphtha?

If the switch is coming Hazardous area especially in fuel oil area like Naphtha, HSD How do I classify it (Hazardous area classification)?

Also clarify me whether explosion proof and flameproof are one and the same. Please throw some light on Explosion proof and Flame proof.

A reply for this is highly appreciable.


anand s

Bruce Durdle


In the context of Intrinsically Safe equipment, (and no other) "simple apparatus" is defined as :
A device that does not generate or store more than 1.2 V, 0.1A, 20 uJ or 25 mW in the intrinsically safe system under normal and fault conditions.
This is from AS2381.7, but the same definition is given in IEC and US codes. Simple apparatus does not need to be certified, but the fact that an
item is being treated as simple apparatus should be noted on documentation.

Specifically, process-operated switches can be classified as simple apparatus and used downstream of an Intrinsically Safe barrier or isolator with no other precautions being needed.

Flameproof and explosionproof are effectively the same. "Flameproof" is the European term: "Explosionproof" is the US term. However, the relevant codes are not identical.

However, please note that the whole field of electrical equipment in explosive ("Hazardous") atmospheres is extremely complex, and really needs
people with specialist knowledge to specify, design, install and maintain the systems. At the very least, you should have a look at the relevant
standards or other material to give an indication of what is involved. I can provide some information in written form, based on Australian/New Zealand standards, if you would find this helpful.

Dear Mr. Bruce Durdle

First of all, I thank for your valuable information.

Next I am interested in knowing more about this.

Moreover, you had said in your mail that you are and you can provide some more information in written form, based on Australian / New Zealand standards, if I find this helpful.

In this context, i would request you send me more information on this.

Thanks once again


anand s