OT: E-Stop Safety Relay

Hi everyone,
I am working on some new panels for a Class 1 Div. 2 application. I am looking for a E-Stop Relay that is rated for Class 1 Div. 2 environments. I haven't been able to find one.

Let me know if you have any ideas.

Thanks!!

Not sure if such a thing actually exists. Have recently been involved in a safety application for an acetylene filling floor and in this situation we used trapped key devices and air operated actuators. The safety controls and subsequent safety dump valve were located outside the hazardous area.

If memory serves Class 1 Div 2 is for the production of explosive gases.

So its all in the NEC as far as what needs to be done. The enclosure for the stop button must be explosion proof (NEMA 4X). The safety relay must also be in an explosion proof enclosure (or else in a different environment). The conduits coming into and out of the enclosure must be sealed to stop keep the gases from entering through them.

I don't think there are any other requirements concerning the safety relay.

The alternative would be to use mechanical or pneumatic safety devices.

Woody - I am finding that out now Thanks

Glen - Class 1 Div 2 is for areas that do not normally contain explosive vapor but can in an abnormal condition. Such as a pipe break or overfill situation.

The panels are actually going to be purged panels in a Class 1 Div 1 area. If I don't use all Class 1 Div 2 components in the panel I have to install a power shut off system if the purge gas gets too low or the door is opened. Since the Panel will have a HMI and require the operator to interface with the panel I cant have the power off if they open the door. I wish I could install it out of the Classified Area but that is not going to be possible in this case.

I am thinking that I will install 2 Hermetically Sealed relays in series to act as a "Safety Relay". I will have the ESD button control the power to the coils. If someone hits the ESD button both relays drop out and if one happens to have "welded" contacts the other should drop the power. I will also have a second set of contacts on the ESD button signal the PLC if it pressed.

If anyone has any other ideas please feel free to share them with me.

Bullzi,

I'm not sure if I understood your last post, but the enclosure must to be purged / pressurized in a Class 1, Div 2 environment based on NFPA 469 - purging / pressurizing electrical enclosures to keep the gases from getting inside and creating an explosion. Your choices for class 1, div 2 are NEMA 4, 4x, 7 and 9. Nema 7,9 being the 1/2" thick enclosures.

Note that there is a rule when purging / pressurizing enclosures that state you can forego certain requirements in regards to killing the power to components IF by doing so you create a more hazardous condition.

You will need to get a copy of the manual, NEC 70, get with the engineering manager, and safety to do a risk assessment.

regards,
james

Bullzi said:

The panels are actually going to be purged panels in a Class 1 Div 1 area. If I don't use all Class 1 Div 2 components in the panel I have to install a power shut off system if the purge gas gets too low or the door is opened. Since the Panel will have a HMI and require the operator to interface with the panel I cant have the power off if they open the door. I wish I could install it out of the Classified Area but that is not going to be possible in this case.

Click to expand...

So are the panels actually in Div 1 or 2? Looks like your first post stated Div 2.
Are you using an X,Y or Z purge? As far as i know requirements are:

If panels are in C1D1:

X purge- have to kill power on purge loss
Y purge - dont have to kill power if panel components are C1D2 rated-must alarm

If panels are in C1D2:

Z purge- don't have to kill power but need a visual/and or audible alarm of loss of purge

no-purge- all items must be C1D2 rated.

The way it is typically done is to use a Cl1Div2 rated E-stop device and a Cl1Div2 rated Zener barrier in the classified area, then put the Safety Relay in a non-classified area. That way you can use a standard enclosure in the classified area, as long as the conduits back to the safe area are sealed.

http://literature.rockwellautomation.com/idc/groups/literature/documents/ca/s117-ca509_-en-p.pdf

James,
The way I understand the requirements for CL1 D2 (and have built UL listed panels for C1D2 locations in the past) is as long as all the components in the panel are rated CL1 D2 then I do not have to purge the panel. This unit will be in a Class 1 Div 1 location.

dginbuffalo,
The panel will be in a Class 1 Div 1 area. In my original post I was just trying to keep it simple and ask about CL1 D2 relays. I plan on using a Y Purge system. So I am going to use all Class 1 Div 2 components to make sure I am compiling with the Y Purge requirements.
Thanks everyone!!

Bullzi,

Please keep in mind that the requirements for a C1D1 environment is more strict than the C1D2 requirements.
When you open the enclosure for what ever reason, the enclosure is now considered C1D1 and the components are rated
C1D2 and you must deal with the power to the system based on the Specifications and the local / state / federal codes.

regards,
james