Process and Application Typicals - FAQ
Following are answers to many frequently asked questions about process and application typicals.
1. What are important requirements for a tracer line trap?
Tracer line traps must be able to perform well under light loads, operate reliably over a long period of time and resist damage caused by freezing.
2. What's the most frequent problem with traps in space heating service?
They tend to be neglected because they are often seen as basic equipment that requires virtually no maintenance.
3. What safety factor is built into IB traps for unit heaters?
IB traps for unit heaters are normally sized with a 3:1 safety factor at the operating temperature differential.
4. What do all types of steam installations require?
Clean, dry steam from the top of the branch line.
5. What requirement must be considered with syphon-drained kettles in addition to those requirements encountered with gravity-drained kettles?
You must be able to handle flash steam effectively.
6. What is the most important requirement for a curing chamber where steam is injected directly into the product chamber?
Curing chambers must handle dirt.
7. If the condensate load can exceed the separating capacity of a flash tank, what type of trap is recommended?
A DC trap.
8. What is the biggest problem in draining condensate from absorption refrigeration equipment?
The low pressure differential in handling the condensate is the greatest concern.
9. Is it OK to trap multiple tracer lines with a single trap?
Even though condensate rates can be small, this is not a good practice.
10. Is size the overriding factor when selecting a trap for a tracer line?
No.
11. Can I elevate condensate after the trap with a constant pressure coil?
Yes.
12. What precaution should I add when elevating condensate after a trap on a modulated pressure coil?
Use a safety drain or a pumping trap.
13. When sizing a trap for a coil application, do I need to worry only about maximum operating pressure?
No. You also should consider the minimum pressure differential.
14. Do I need to apply a safety factor when using SHEMA ratings to size F&T traps?
No.
15. Do process air heaters generally operate at higher temperatures than space heating coils?
Yes.
16. Are disc and thermostatic traps good choices in syphon lifting applications?
No.
17. Can condensate be returned to the boiler in direct steam injection applications?
No.
18. Does live steam or flash steam have the greater energy and heat value?
At the same pressure, flash steam has the greater energy and heat value.
19. What is the proper pitch direction for tracer lines?
Pitch the tracer line in the direction of flow to promote gravitational drainage.
20. What is the safety factor for tracer line applications?
Use a 2:1 safety factor.
21. What can happen if there is a steam trap failure in space heating equipment?
Failed steam traps waste a great deal of energy. Throw in some freezing conditions, and retained condensate can add substantial damage. If the trap fails closed, there may also be the possibility of water hammering and increased corrosion.
22. What do I need to consider when using a safety drain?
Make sure the discharge of the safety drain is drained by gravity.
23. What temperatures are possible with process heat applications?
Temperatures of 500° F (260° C)are not uncommon.
24. What is the function of submerged coils in steam systems?
Submerged coils can heat water for industrial or domestic use, vaporize industrial gases such as propane and oxygen, and heat fuel oil for easy transportation and atomization.
25. Is the float and thermostatic trap the preferred choice for all syphon drainage applications?
No.
26. What precaution should be taken with steam jacketed presses?
Each platen should be trapped separately.
27. How is flash steam formed?
Flash steam is formed when high-pressure condensate is let down to a lower pressure.
28. Does flash steam or live steam have the higher BTU value?
Flash steam has a higher BTU value than live steam at the same pressure.
29. What is "short circuiting"?
This hazardous practice runs several tracing lines to one trap.
30. What are the requirements for a tracer-line steam trap?
Tracer-line steam traps must resist freezing and wear. They must also be able to perform well under light loads.
31. What is the best trap to use for tracer-line applications?
An inverted bucket trap.
32. How can I prevent backflow when trapping process heaters with modulating pressures and elevated return lines?
Install a pumping trap with a check valve downstream, and install a safety drain with an integral vacuum breaker.
33. What requirements are most important in selecting a trap for constant-pressure process air heaters?
Select a trap that can operate against back pressure and respond immediately to slugs of condensate.
34. What trap is the best choice for a shell and tube heat exchanger?
An F&T trap.
35. What trap is the best for an evaporator?
A differential condensate controller.
36. Should I use a thermodynamic trap in a constant-pressure heating coil application?
No
37. When should I use a vacuum breaker?
Use a vacuum breaker on applications with modulating steam pressure.
38. Is the same safety factor used for all steam trap applications?
No.
39. Should a drip trap and strainer be used ahead of the control valve or PRV?
Yes.
40. Is it OK to elevate condensate on the discharge side of a steam trap?
No. Elevating condensate on the discharge side of a steam trap can present problems on a modulating system.
41. When should a pump trap be used in a modulating system?
Use a pump trap if condensate must be lifted in the system.
42. Is it acceptable to use one trap on two pieces of heat exchanging equipment as long as they're located close together?
No.
43. Should I install a test valve downstream from a steam trap?
Yes. This is good piping practice.
44. What is the least costly way to protect modulating systems?
A safety drain is the least costly way to protect equipment from damage if you are not concerned about discharging concentrate into the sewer system.
45. When do I use the SHEMA ratings to size a steam trap?
SHEMA ratings apply only to an F&T trap.
46. Do I need more than one trap for multiple kettles that are used at the same time and heat the same amount of product?
Yes. Each should be trapped separately.
47. Is all the condensate retained in a syphon-drainage application?
No. A percentage of the condensate flashes to steam as it is picked off the wall of the dryer, and it is discharged.
48. Do I need to install a back-pressure regulator on a flash tank to control pressure?
No.
