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Thermodynamic

Thermodynamic Traps

The Thermodynamic Trap is simple and compact with a single moving part (disc) which opens to discharge condensate and closes in the presence of steam. Body materials available are Stainless and Alloy Steels for pressures up to 3,600 psig. Widely used on higher pressure drip applications and critical tracing applications (where condensate back-up is not permitted).

  • Rugged design and excellent for use with superheated steam
  • Operation is easy to check due to distinct cyclic operation
  • Single model operates over a wide pressure range in contrast to mechanical traps
  • Self-draining when mounted vertically to prevent freezing
Product Models Characteristics Material Application
TD600  
No Strainer

The one piece body-seat design is extremely simple, rugged and economical, however, they are not fully in-line repairable. Trap body cannot be welded in-line.

420 Stainless Steel Drip & Tracing Applications
30 to 600 psig
TD600S 
Strainer
TD700S 
Replacement 
Capsule Feature

In-line Repairable Seat & Body are non-integral. Replacement capsule allows for complete repair without removing trap body from piping system. Can be welded in-line.

Alloy Steel Drip & Tracing Applications
30 to 600 psig
TD900S

In-line Repairable Seat & body are non-integral; allows for complete repair without removing trap body from piping system. Can be welded in-line.

Alloy Steel Drip Application 
High-Pressure to 900 psig
TD3600

Ultra High-Pressure 3600 PSIG
In-line Repairable Can be welded in-line

Alloy Steel Drip Application 
Ultra High-Pressure to 3600 psig

Applications

The primary use of the thermodynamic trap is for draining condensate formed in steam lines (drip applications) with pressures over 30 psig, for pressure under 30 psig thermostatic or F&T traps are generally preferable. For tracing applications that can not tolerate any condensate back-up (referred to as critical tracing) thermodynamic traps are used instead of thermostatic traps. advantages of the thermodynamic trap is that a single model operates over the full pressure range, they can operate on superheated steam, and will self drain preventing frozen pipelines in cold climates.

Thermodynamic Traps are Normally not recommended on process applications because of their limited ability to purge air from the steam system which is required during start-up.

Drip Leg in a Steam Main

Drip Leg Design Criteria:

  • For systems with automatic start-up, L to be 28” minimum (= 1 PSI minimum head pressure)
  • Drip leg diameter should be equal to steam main diameter (up to 4” in size)

Drip Leg Before Regulator or Control Valve

Drip Legs should be installed directly ahead of regulators and control valves to minimize erosion to valve trim and flooding of valve bodies.

Thermodynamic Traps Shown in Tracing Applications

In both images below stainless steel or copper tubing containing pressurized steam is place in close contact to the piping system carrying a liquid that requires its temperature to be heated. The piping system would then be wrapped in insulation to reduce heat loss and maximize heat transfer from the tracing line to the product being heated. Steam Tracing is used to prevent freezing or to allow product to flow easier by reducing product viscosity.

Thermodynamic Trap

Thermodynamic traps have only one moving part, the valve disc, which allows condensate to be discharged when present and closes tightly upon the arrival of steam. These traps have an inherently rugged design and are commonly used as drip traps on steam mains and supply lines. Their solid construction and single moving part make them resistant to waterhammer and are freeze-proof when installed vertically. Thermodynamic traps will only discharge small amounts of air and therefore are typically not used in process applications.

Valve Disc Open

When condensate is present, trap remains in the open position allowing condensate to discharge. Steam pressure pushes the condensate thru the trap.

Valve Disc Starting to Close

When steam enters the trap, it creates an internal pressure above the disc that instantly forces the disc and seat to close tightly, preventing steam from escaping.

Valve Disc Closed

Steam pressure above the disc holds the disc closed, trapping steam in the system. Trap will remain closed until the steam above the disc condenses, due to heat loss through the cap.

How-To-Size

Drip applications refer to the removal of condensate formed in steam lines due to the radiant heat loss of the hot steam pipes to surrounding air and are required for the protection of the steam system. (Drip Traps remove the condensate from the steam lines where the process traps remove condensate being generated by the actual process.) Drip traps should be placed 150 to 300 feet apart on straight runs of piping, before elevation changes, and before critical equipment such as Regulators and Control Valves.

Why Condensate Safety Load Factors and Warm-up Loads need to be considered:
During start-up, when the piping system is cold and steam begins to flow thru the pipes, steam is condensing very quickly because of the energy required to heat all the cold surfaces. Furthermore, the steam pressure in the system which is required to push the condensate through the steam trap into the return line, is low before the system comes up to full pressure. Therefore, condensate is being generated at a maximum rate and the steam pressure used to push the condensate out of the system is at a minimum. If the traps are sized for the normal running loads and normal system pressures, then they would be undersized for the start-up condition. In a supervised start-up, condensate drain valves located throughout the system, are manually opened to drain excessive condensate generated by the cold piping system; relying less on the steam traps. Therefore, the steam traps selected for a system with a supervised start-up can be more closely sized for the actual normal running load.

Sizing Example: Size a drip trap for an 8” steam main with 100 psig steam pressure. Traps should be placed every 200 ft. A 2x safety factor based on Warm-Up load will be used.

• Based on Warm-Up Load Chart: 100 lbs/hr of condensate is generated per 100 feet length of pipe.
• Warm up load for 200 ft. length is therefore, 200 lbs/hr (2 x 100 lbs/hr)
• If a 2x safety factor based on warm-up load is used, we require a trap with a capacity of 400 lbs/hr
• Actual running load for 100 ft. length = 41 lbs/hr
• Actual running load for 200 ft. length = 82 lbs/hr

Warm-Up Loads in Pounds of Condensate per hour per 100 ft. of Steam Main

Running Loads in Pounds of Condensate per hour per 100 ft. of Steam Main

Trap Selection: Reference the TD600S Series Capacity Chart below based on inlet steam pressure. Enter the chart under 100 psig inlet pressure to compare the capacities of different models.

The 1/2” TD600LS will be capable of discharging 375 lbs/hr of condensate at 100 psig steam pressure. The capacity is slightly less than the load calculated based on warm-up load with 2x safety factor, however, this trap selection would be a suitable choice since its capacity is well in excess of what is actually required. These loads are indicative of drip applications and lend support as to why only reduced capacity 1/2" TD600L or 3/4" TD600L traps are required for the majority of drip applications.

DRIP, TRACING: The TD600 is Non-Repairable and commonly used as a drip trap on steam mains and steam supply lines. Ideal for outdoor applications that are subject to freezing and for super heated steam conditions.

The TD600L is Reduced Size Discharge Orifice holes which are preferable in terms of performance, longevity, and efficiency; particularly on pressure over 150 psi

ModelSizeTypeOptionsMax PMO (psig)Max Capacity @ Max PMO (lb/h)
TD600L-12-N1/2"NPTL600
TD600L-13-N3/4"NPTL600
TD600-11-N3/8"NPT600
TD600-12-N1/2"NPT600
TD600-13-N3/4"NPT600
TD600-14-N1"NPT600

DRIP, TRACING: The TD600S is Non-Repairable and commonly used as a drip trap on steam mains and steam supply lines.  Supplied with integral strainer and optional blowdown valve to protect trap from contamination. Ideal for outdoor applications that are subject to freezing and for super heated steam conditions.
The TD600LS is Reduced Size Discharge Orifice holes which are preferable in terms of performance, longevity, and efficiency; particularly on pressure over 150 psi

ModelSizeTypeOptionsMax PMO (psig)Max Capacity @ Max PMO (lb/h)
TD600LS-12-N1/2"NPTLS600
TD600LS-13-N3/4"NPTLS600
TD600LS-14-N1"NPTLS600
TD600LSB-12-N1/2"NPTLS, Blowdown600
TD600LSB-13-N3/4"NPTLS, Blowdown600
TD600LSB-14-N1"NPTLS, Blowdown600
TD600S-12-N1/2"NPT600
TD600S-13-N3/4"NPT600
TD600SB-12-N1/2"NPTBlowdown600
TD600SB-13-N3/4"NPTBlowdown600

DRIP, TRACING: The TD700S  Thermodynamic steam trap is commonly used as a drip trap on steam mains and steam supply lines. These traps are used on tracing applications; however, thermostatic traps are normally recommended for this service. Supplied with an integral strainer and optional blow down valve to protect the trap from contamination. The internal working mechanism of the TD700S can be completely replaced while the trap body remains in line. Ideal for outdoor applications that are subject to freezing and for super heated steam conditions.

ModelSizeTypeOptionsMax PMO (psig)Max Capacity @ Max PMO (lb/h)
TD700S-12-N1/2"NPT600
TD700S-13-N3/4"NPT600
TD700S-14-N1"NPT600
TD700S-12-SW1/2"Socket Weld600
TD700S-13-SW3/4"Socket Weld600
TD700S-14-SW1"Socket Weld600
TD700S-12-F1501/2"150# FLG600
TD700S-13-F1503/4"150# FLG600
TD700S-14-F1501"150# FLG600
TD700S-12-F3001/2"300# FLG600
TD700S-13-F3003/4"300# FLG600
TD700S-14-F3001"300# FLG600
TD700S-12-F6001/2"600# FLG600
TD700S-13-F6003/4"600# FLG600
TD700S-14-F6001"600# FLG600
TD700HS-12-N1/2"NPTHS600
TD700HS-13-N3/4"NPTHS600
TD700HS-14-N1"NPTHS600
TD700HS-12-SW1/2"Socket WeldHS600
TD700HS-13-SW3/4"Socket WeldHS600
TD700HS-14-SW1"Socket WeldHS600
TD700HS-12-F1501/2"150# FLGHS600
TD700HS-13-F1503/4"150# FLGHS600
TD700HS-14-F1501"150# FLGHS600
TD700HS-12-F3001/2"300# FLGHS600
TD700HS-13-F3003/4"300# FLGHS600
TD700HS-14-F3001"300# FLGHS600
TD700HS-12-F6001/2"600# FLGHS600
TD700HS-13-F6003/4"600# FLGHS600
TD700HS-14-F6001"600# FLGHS600
TD700SB-12-N1/2"NPTBlowdown600
TD700SB-13-N3/4"NPTBlowdown600
TD700SB-14-N1"NPTBlowdown600
TD700SB-12-SW1/2"Socket WeldBlowdown600
TD700SB-13-SW3/4"Socket WeldBlowdown600
TD700SB-14-SW1"Socket WeldBlowdown600
TD700SB-12-F1501/2"150# FLGBlowdown600
TD700SB-13-F1503/4"150# FLGBlowdown600
TD700SB-14-F1501"150# FLGBlowdown600
TD700SB-12-F3001/2"300# FLGBlowdown600
TD700SB-13-F3003/4"300# FLGBlowdown600
TD700SB-14-F3001"300# FLGBlowdown600
TD700SB-12-F6001/2"600# FLGBlowdown600
TD700SB-13-F6003/4"600# FLGBlowdown600
TD700SB-14-F6001"600# FLGBlowdown600
TD700HSB-12-N1/2"NPTHS, Blowdown600
TD700HSB-13-N3/4"NPTHS, Blowdown600
TD700HSB-14-N1"NPTHS, Blowdown600
TD700HSB-12-SW1/2"Socket WeldHS, Blowdown600
TD700HSB-13-SW3/4"Socket WeldHS, Blowdown600
TD700HSB-14-SW1"Socket WeldHS, Blowdown600
TD700HSB-12-F1501/2"150# FLGHS, Blowdown600
TD700HSB-13-F1503/4"150# FLGHS, Blowdown600
TD700HSB-14-F1501"150# FLGHS, Blowdown600
TD700HSB-12-F3001/2"300# FLGHS, Blowdown600
TD700HSB-13-F3003/4"300# FLGHS, Blowdown600
TD700HSB-14-F3001"300# FLGHS, Blowdown600
TD700HSB-12-F6001/2"600# FLGHS, Blowdown600
TD700HSB-13-F6003/4"600# FLGHS, Blowdown600
TD700HSB-14-F6001"600# FLGHS, Blowdown600

DRIP: The TD900S Thermodynamic steam trap is primarily used as a drip trap on high pressure steam mains and steam supply lines when a repairable trap type is desired. Ideal for outdoor applications that are subject to freezing and for super heated steam conditions. The TD900LS is recommended for pressure over 300 PSI.

ModelSizeTypeOptionsMax PMO (psig)Max Capacity @ Max PMO (lb/h)
TD900S-12-N1/2"NPT900
TD900S-13-N3/4"NPT900
TD900S-14-N1"NPT900
TD900S-12-SW1/2"Socket Weld900
TD900S-13-SW3/4"Socket Weld900
TD900S-14-SW1"Socket Weld900
TD900S-12-F6001/2"600# FLG900
TD900S-13-F6003/4"600# FLG900
TD900S-14-F6001"600# FLG900
TD900LS-12-N1/2"NPTLS900
TD900LS-13-N3/4"NPTLS900
TD900LS-14-N1"NPTLS900
TD900LS-12-SW1/2"Socket WeldLS900
TD900LS-13-SW3/4"Socket WeldLS900
TD900LS-14-SW1"Socket WeldLS900
TD900LS-12-F6001/2"600# FLGLS900
TD900LS-13-F6003/4"600# FLGLS900
TD900LS-14-F6001"600# FLGLS900

DRIP: The TD3600 Thermodynamic steam trap is commonly used as a drip trap on high-pressure steam mains and steam supply lines. Supplied with an integral strainer to protect the trap from contamination. The internal working mechanism of the TD3600 can be completely replaced while the trap body remains in line. Ideal for outdoor applications that are subject to freezing and for super heated steam conditions.

ModelSizeTypeOptionsMax PMO (psig)Max Capacity @ Max PMO (lb/h)
TD3600-12-SW1/2"Socket Weld3600
TD3600-13-SW3/4"Socket Weld3600
TD3600-14-SW1"Socket Weld3600
TD3600-12-BW1/2"Butt Weld3600
TD3600-13-BW3/4"Butt Weld3600
TD3600-14-BW1"Butt Weld3600
TD3600-12-F6001/2"600# FLG3600
TD3600-13-F6003/4"600# FLG3600
TD3600-14-F6001"600# FLG3600
TD3600-12-F15001/2"1500# FLG3600
TD3600-13-F15003/4"1500# FLG3600
TD3600-14-F15001"1500# FLG3600

DRIP, TRACING: Designed to work as a drip traps for the draining of condensate from steam mains and other steam supply lines, The UTD450 Thermodynamic Steam Trap Module can be used anywhere. Can also be used on tracing applications. The module mounts to any 2-bolt Universal Connector. This model is only recommended for horizontal piping installations to allow the cap to be oriented upwards.

ModelSizeTypeOptionsMax PMO (psig)Max Capacity @ Max PMO (lb/h)
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DRIP, TRACING: Designed for drip applications for the draining of condensate from steam mains and other steam supply lines as well as for tracing applications. The UTD450SM and UTD600LSM Thermodynamic Steam Trap Modules can be used anywhere. This traps module can be used on either vertical or horizontal piping installations and can mount to any 2-bolt Universal Connector.

ModelSizeTypeOptionsMax PMO (psig)Max Capacity @ Max PMO (lb/h)
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