Thermodynamic Steam Trap; Pressure needed to Drive

In summary, the differential pressure requirement for a typical thermodynamic steam trap to discharge condensate is not much, usually around 100 mmHg or 0.13 bar. However, in this specific case, the receiving vessel has a higher vacuum, so it may be necessary to use a more complex and expensive "pumping steam trap". It is important to consult with a rep from Armstrong or Sarco to determine the best trap type for the specific application, as different trap types have varying requirements for differential head. Thermostatic types may not be suitable for vacuum applications and low temperatures, while float or inverted-bucket types are more positive-acting in these conditions.
  • #1
rollingstein
Gold Member
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How much of a differential pressure does a typical thermodynamic steam trap need to discharge condensate?

i.e. Say one needs to drain condensate from a shell under vacuum 310 mmHg abs, would a thermodynamic steam trap work correctly if I connected the discharge pipe to a vessel maintained at 210 mmHg abs i.e. A differential pressure of 100 mmHg i.e. 0.13 bar.

This is a small 1/2" trap & the expected condensate isn't much. Approx. 100 to 250 Litres / hour. The discharge piping is very short (say 6 feet long) since the vessel is very close to the trap.

An image of the trap type just for context.

f-s-thermodynamic-steam-trap_1.jpg
 
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  • #2
Not much delta-P is needed; however, you're indicating a higher pressure in the receiving vessel?
 
  • #3
insightful said:
Not much delta-P is needed; however, you're indicating a higher pressure in the receiving vessel?

Arrgh! My bad. Messed up my spreadsheet. I've corrected the numbers now.

And indeed I'm having a lower pressure in the receiving vessel. i.e. A higher vacuum in the receiving vessel.

So, you think with just a 100 mmHg delta P the typical steam trap would drain condensate correctly? That would be awesome for my purposes. I was worried about having to mess around with the more complex and expensive "pumping steam traps".

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  • #4
Well, 100mmHg is only about 4.5 ft of head so you'd have to make sure your elevation differences don't cause a problem. As usual, the final answer should come from your Armstrong or Sarco rep.
 
  • #5
insightful said:
As usual, the final answer should come from your Armstrong or Sarco rep.

Any idea if they note the differential head needed on the trap spec sheets? I couldn't find it on any I have on file. Just wondering.

Also, among the various trap types any idea which one can do with the least head requirement? Are there big variations? Or not really.
 
  • #6
rollingstein said:
Any idea if they note the differential head needed on the trap spec sheets? I couldn't find it on any I have on file. Just wondering.

Also, among the various trap types any idea which one can do with the least head requirement? Are there big variations? Or not really.
I'm going to back-peddle. Your vacuum application and subsequent low temperatures might not work with thermostatic types. Float or inverted-bucket types are more positive-acting for these conditions. Yeah, the web sites talk about "up to" capacities but no curves. Talk to a rep.
 

What is a thermodynamic steam trap?

A thermodynamic steam trap is a type of valve used in steam systems to discharge condensate and non-condensable gases while preventing steam from escaping. It operates based on the principle of thermodynamics, using the difference in pressure between steam and condensate to open and close the valve.

How does a thermodynamic steam trap work?

A thermodynamic steam trap consists of a valve and a disc, which is held in place by a spring. When steam enters the trap, it lifts the disc against the spring, allowing the steam to pass through and be discharged. When condensate or non-condensable gases enter, the disc closes, preventing their escape while still allowing steam to pass through.

What is the purpose of a thermodynamic steam trap?

The primary purpose of a thermodynamic steam trap is to remove condensate and non-condensable gases from a steam system, while ensuring that steam is not wasted. This helps to maintain the efficiency and effectiveness of the steam system, as well as prevent damage to equipment and pipes due to condensate buildup.

How much pressure is needed to drive a thermodynamic steam trap?

The exact pressure needed to drive a thermodynamic steam trap may vary depending on the specific design and operating conditions. However, in general, a minimum pressure of 1 bar (14.5 psi) is typically required to operate a thermodynamic steam trap effectively.

What are the benefits of using a thermodynamic steam trap?

There are several benefits to using a thermodynamic steam trap, including its ability to handle high condensate loads, its simple and reliable design, and its ability to work in a wide range of temperatures. Additionally, it does not require any external power source and has a long lifespan, making it a cost-effective option for steam systems.

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