Gas group IIA vs IIB, IIC

[charz]

How common (as a standard product) is the availability of gas group Ex de IIA, Ex ec IIA motors?
As I could see from our past projects, most LV motors are with gas group IIB, so IIB looks more common.
The concern here is that vendor is offering gas group IIC for some motors; if I accept the IIC motors now, future replacements would also need to be IIC-certified or just replace it with IIA. Which would be IIA or IIC advisable now considering the immediate availability and cost for future replacements.

 

[Gr8blu]

In the IEC world, the gas groups IIA, IIB, and IIC are classifications used to categorize flammable gases based on their ignition properties:
Group IIA: Contains gases that require a lower energy to ignite, such as propane and butane.
Group IIB: Includes gases that require a higher energy to ignite than IIA, such as ethylene and most petrochemical gases.
Group IIC: Represents gases that require the highest energy to ignite, including hydrogen and acetylene.

These classifications are important for selecting appropriate explosion-proof equipment in hazardous areas.

In general, any machine rated for IIA can be replaced by one rated for IIB or IIC. However, a IIC can only be replaced by a IIC.

Note the difference in IEC vs North American standards: for IEC, as the alphabet letter increases, so does the required energy ( A < B < C). For North America, it is the other way around - a low letter means more energy (A > B > C > D).

 

[charz]

In the IEC world, the gas groups IIA, IIB, and IIC are classifications used to categorize flammable gases based on their ignition properties:
Group IIA: Contains gases that require a lower energy to ignite, such as propane and butane.
Group IIB: Includes gases that require a higher energy to ignite than IIA, such as ethylene and most petrochemical gases.
Group IIC: Represents gases that require the highest energy to ignite, including hydrogen and acetylene.

These classifications are important for selecting appropriate explosion-proof equipment in hazardous areas.

In general, any machine rated for IIA can be replaced by one rated for IIB or IIC. However, a IIC can only be replaced by a IIC.

Note the difference in IEC vs North American standards: for IEC, as the alphabet letter increases, so does the required energy ( A < B < C). For North America, it is the other way around - a low letter means more energy (A > B > C > D).

Does that mean IIA, IIB & IIC motors of same rating would have the same frame size? and there would no be issue during replacement? Which gas group is available immediately in the market so that delivery times are lesser?

 

[mparenteau]

You'll have to do your due diligence and check the frame sizes with the corresponding motor group. Also, be careful with AIT and any VFD applications as it pertains to motor inverter duty capability.

Mike

PS for example, you may have a motor spec that gives a T3C temperature code for a sine wave application, but T3 for a VFD application (inverter duty).

 

[Gr8blu]

@Op Except for some very specific ratings, most IIA, IIB, and IIC machines are custom. The likelihood that a machine with one classification will exactly match one of another classification is slim to none, even if both are manufactured by the same entity.

In addition, the allowable enclosure types vary with the gas group as well. IIC machines are likely to be totally enclosed, for example, with purge and/or pressurization systems.