Freeze Protection for Piping

[anks]

hi,

can anyone guide me on how to go with freeze protection on piping, is there any standard products available or that is something to be custom made?? also will that be controlled through the PLC inside the control panel or is something kind of isolated control circuit??
we had a pipe cracks on couple of jobs due to cold weather & we are planning on implementing a freeze protection circuit on few job site, any help will be appreciated.

thanks

 

[Oakley]

heat trace - electric

steam trace - steam

 

[ahackwor]

I have used Delta-therm heat trace on pipes and thermon heat pads for tanks. Worked great.

http://www.delta-therm.com/
http://www.thermon.com/


You could use a simple thermostat to turn the heat trace on and off, or you could wire an RTD to the PLC and use the temperature signal to energize a control relay which turns power on to the heat trace.

Keep in mind that this is a "power" circuit, not a "control" circuit. Power to the heat trace could come from a GFCI breaker in a lighting panel, or from your control panel if it can handle the load.

 

[anks]

thnx a lot

 

[elevmike]

http://www.heatersplus.com/pipe.htm

 

[danw]

There's a whole electric heat trace market out there, with firms who specialize in heat trace.

Heat trace elements are designed to keep insulated pipes warm enough to prevent freeze up of the medium. The key is insulated. It can be frustrating to try heat trace uninsulated pipes because the heat loss just can't be replaced.

For electric heat there are two types of heaters
Self regulating is a flexible tape that is wrapped around the pipe and does what its name implies, it self regulates within a temperature band.

Rigid or Mineral insulated (MI) cable is 1/4" diameter stainless or copper tubing with heater elements inside, insulated from the tubing by powdered insulation. It is wrapped around the pipe and strapped to the pipe with SS wire. Sometimes the heater is formed into an S snake shape to get the required watts per foot necessary for protection. The heat capacity of MI cable is higher than of self regulating so it's used for industrial apps where the maintainence temperature is higher. It's also used in concrete for ice free sidewalks, loading dock pads and ramps and such. MI needs some form of temperature control. There are RTDs that are designed to be strapped to a round pipe as sensors.

The required wattage for the heaters should be calculated from the maintenance temperature, pipe size and length of run, insulation qualities (R factor, thickness), wind, protection level (lowest expected temperature exposure. The heater vendors have software for sizing.

Signs should be posted to warn that there's electric heat trace under the insulation.

Control is just on-off, with an output driving a contactor large enough to carry the current. Small jobs without a PLC use a thermostat or little single loop controllers.

Here's a link to a mineral insulated installation guide

http://www.nelsonheaters.com/DownLo...MANUAL%20IM.pdf