Disk Traps Troubleshooting and Maintenance

Procedures. The contact area between the disk and its seat can become corroded or blocked, and this can cause a problem. Other problems may include installation backward to the proper direction of steam flow. To maintain this trap, first check the installation to see if the manufacturer's directions have been followed. Then, if installation is correct, valve off the trap from live steam, remove the top, and check on the condition of the disk and its contact surface. Unlike the bucket traps, this trap has no prime, so losing its prime is not a problem.

Thermostatic Traps

This trap operates on the general principles illustrated in Figure 14.10. In this trap, the bellows or bimetallic strips are extended when hot and contracted when cold. Since condensate is cold (relative to steam), its pressure causes the tap to contract, opening the outlet and allowing condensate and noncondensable gases such as air and carbon dioxide to escape. When these have left the trap, steam comes in and heats up the bellows or bimetallic strip. This expands, closing the outlet. As steam condenses, the quantity of condensate builds up, the valve opens again, and the cycle repeats. This

trap can be used to give a continuous flow of condensate if desired.

Thermostatic Traps, Troubleshooting and Maintenance. Depending upon the mounting of the trap, dirt and scale may not be a problem in the outlet. If the bellows leaks and fills with condensate, the trap may fail instead. If a bimetallic strip is used instead of bellows, corrosion can be a problem. Like most other traps, failure can be caused in this trap if scale or dirt gets between the valve and its seat. Also, the dirt screen can get plugged up, causing the trap to fail closed.

Steam Distribution System, Maintenance Frequency

The steam distribution system, including piping, steam-heated equipment, steam traps, and the condensate return system, should be checked regularly for leaks and to ensure correct operation. The frequency of inspection should vary with the age of the installation—in a new system, dirt and other foreign matter in the pipes will be deposited in strainers, steam traps, and the bottom of steam-heated equipment. After the installation of a new system, it thus makes sense to check steam traps, strainers, and drains frequently, perhaps every 3 months. As the system gets older, scale can become a problem if the water is not properly treated. If scaling is a problem, the steam distribution system will have to be maintained more often than without scaling—semian-nually rather than annually, for example, on steam trap inspection. The entire steam system should be inspected carefully at least once each year for leaks and to keep steam traps and steam-heated equipment operating correctly. When this inspection and maintenance procedure is followed regularly, the amount of steam needed will be reduced, and the cost savings will be substantial.

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