How is the hot gas defrosting in low temperature cold storages are carried out. Seeking an elaborate answer containig what all valves to be closed and opened and whether the compressor is to be stopped or running during the defrosting.

How is the hot gas defrosting in low temperature cold storages are carried out. Seeking an elaborate answer containig what all valves to be closed and opened and whether the compressor is to be stopped or running during the defrosting.hot gas defrost... using hot gas (freon) to defrost; of course the compressor is running... try looking it up in WIKIPEDIA... it also use in ice machine

Look at your system's piping schematic. Notice the hotgas bypass (bypassing the condenser) valve. This will generally be a 3-way cutting out condenser liquid... and allow hot gas straight from the compressor to go straight to the evap... yes the compressor runs during this.
You should call a profressional refer guy to handle this... unless the sequence is an automatic from a panel switch. If you don't know which refrigerant you are using in the system... or which valve is the bypass valve or how it is actuated... you should not initiate this process - you might damage the system.
Hope this helps.

Hi, Valves arrangement for Hot Gas Defrosting of natural circulation, pump recirculation, and direct expansion system is different . You can check out Frost Defrost Controller | Frost Control | Electronic Frost Defrost Controller (http://www.manikengineers.com/Frost-Defrost-Control-System.html) for operation valves and timing.
Regards
Anand