Hussmann Rack

[NANOTECH]

What is the " Ruptured Disk Alarm " on a Hussmann Rack?

[icemeister]

This is just a guess, but it may be a relief valve alarm.

I've never seen one but supposedly there's a rupture disc in the relief valve vent line with a pressure sensor in between it and the relief valve which senses a rise in pressure and thus triggers an alarm.

[jpsmith1cm]

This is just a guess, but it may be a relief valve alarm.

I've never seen one but supposedly there's a rupture disc in the relief valve vent line with a pressure sensor in between it and the relief valve which senses a rise in pressure and thus triggers an alarm.

[icemeister]

You mean I guessed right?

They must have modified the relief valve venting code to allow for that one.

[thefreezerguy]

Yep, that's what they are. Once the diaphragm inside ruptures from the relief valve opening there will be pressure in the rupture disk valve closing a set of contacts. This lets the controller know of the event. They are non resettable. Once they have flow go through them they must be replaced. I have only seen them ruptured on a new receiver that we were installing. The OEM must have hit the relief limit somehow at the factory.

[Phase Loss]

the rupture valve, aka redundant high head condition alarm.

never mind that your rack has high pressure safety's and pressure transducers mounted on the high side. Lets add yet another monitoring feature ( the rupture disk) while its job could already be accomplished via~the several other already mounted controls/sensors.

I need to invent such a redundant control and sell it to manufactures...how about the Pre oil failure oil failure control?

[Phase Loss]

to add to my post, I have never seen the rupture disk mounted in the relief valves vent line. All of the applications I see have the rupture disk installed in between the relief valve and the vessel as seen in the following link http://www.henrytech.com/catalog/2010/h20-h21.pdf

[thefreezerguy]

to add to my post, I have never seen the rupture disk mounted in the relief valves vent line. All of the applications I see have the rupture disk installed in between the relief valve and the vessel as seen in the following link http://www.henrytech.com/catalog/2010/h20-h21.pdf

That's how I've seen them installed as well. They wont work if installed after. Well, It might for a short time until the relief closes back up that is. As to yet another high head alarm, Whatever sells right??? I do like your upcoming pre oil failure oil failure device!

[NANOTECH]

Thanks for the great info! Had a power outage at this store and when it was restored the 8RO for the condensers didnt come back online. When I got there, comps were cycling on high head (350psig) and the Ruptured Disc Alarm was on. From what Im reading here even though the relief valve is closed the pressure is still in the RDV keeping the contacts closed (Alarm) and the only way to rectify this is changing the valve!

[jpsmith1cm]

Is the 8RO board wired to fail those fans to 100%.

[Gnarly]

The 8ro boards for the condenser should fail in the n.c. position. I would check the dip switches. I think they should be in the up position for fail safe.

[NANOTECH]

Interesting questions about the 8ro's! The rack when I got there sounded like a freight trane, I turned the control circuit of and back on and first thing I seen was the condenser fans comming back online and the discharge pressure dropping!!!!! I was happy-- at that point my suction header was at 90psig!! I will have to do a follow up and look at them dam dip switches. Your right!! I would definetly think that them CFM's should have failed closed!!

[Hard4mrkts]

Also the 8ro board could be, depending on manufacturer, set to invert the n.c. contacts of the relay be sure to completly test the controls. Including dropping power to the rack again and see what happens ( be ready!!). The head saftey set points are set to high for the refrig. being used or the wrong releif valve has been installed. Their should be enough difference between the two controls (head pressure saftey and releif valve)to keep this from happening. If their has been a gas change to the rack maybe someone adjusted the head saftey and did not replace the releif valve. Normal operation you use the head saftey to shut off. Fire or other huge oh shoot you want redundency. I think it might evan be a pressureized vessel standard. Good luck.