Comparing Mechanical Steam Traps

Comparing Mechanical Steam Traps

Comparing Mechanical Steam Traps: Ball Float & Inverted Bucket Traps on the Steam Main

     Two types of mechanical steam traps are found on the mains of commercial and some residential steam systems: Ball Float steam traps and Inverted Bucket steam traps. These explanations are adapted from Spirax Sarco's excellent free online tutorial found at the citation we provide below. Quoting from Spirax Sarco, a producer of all types of steam traps.

     Mechanical steam traps rely on the difference in density between steam and condensate in order to operate. They can continuously pass large volumes of condensate and are suitable for a wide range of process applications. Types include ball float and inverted bucket steam traps.

The photographs of mechanical steam traps shown below can aid in recognition of these features on steam heat systems.

Table of Brands & Models of Steam Traps with Identifying Photographs

Mechanical Steam Trap Brand & Model Steam Trap Photo Comments
Armstrong International 813 Inverted Bucket Steam Trap 3/4" NPT, 2" NPT
Operating Pressures to 125
Horizontal steam piping
Armstrong inverted bucket steam traps handle differential pressures according to model series:
Series 200 & 800: 10 - 125 psi
Series 300: 125 - 600 psi
Series 400: 600-1000 psi
The products vary in capacity measured in pounds per hour from 300 to 25,000 or measured in kg/hr fro 150 to 10,000 kg/hr
Armstrong International #1811 Steam Trap 3/4" NPT
Stainless steel
Operating Pressures to 125 psi
Clark Reliance 119 Inverted Bucket Steam Trap 3/4" NPT
20 psi
Inverted bucket steam trap
Hoffman Series B1 Inverted Bucket Trap for Steam Mains Hoffman 404300 B1015A-2 (at left)
Hoffman Specialty B3125A-5 B3125A4 404427 Bucket Trap operates at up to 250 psig.
1/2" NPT, 3/4" NPT, other
Inverted Bucket Steam Trap
Used on steam mains, laundry steam piping & other. These traps are also found painted other colors such as a gray-green.
ITT Hoffman Specialty, Indianapolis IN, USA. Trap data tags typically indicate model, size (NPT), maximum pressure differential, a maximum allowable pressure (e.g. 250 psig at 425°F, and a date code.
ITT B3030A Steam Trap 1" NPT
30 psi
Juker SA8 Inverted Bucket Steam Trap Juker P/N SA 8 SA-8
1/2" NPT
Top fitting 1/4" NPT
Pennant Steam Trap
Spence Engineering 84-CSF9 Steam Trap Inverted bucket steam tarp
250 psi
1 ,1/4" NPT
Spence Nicholson 80s Steam Trap 3/4" NPT
United 850 Steam Trap Model 850 1/2" steam trap
50-200 psi
Other similar steam trap models: Model 849 1/2", Model 849A/B 3/4" steam trap
United Brass Works, Inc,
Watts Thermostatic Radiator Steam Trap These traps are recommended for use at the outlet of steam radiators and steam convector heaters. When the radiator is cool the trap opens to allow discharge of air (allowing steam into the radiator) and cooled condensate that may be in the radiator bottom
When the radiator and thus the condensate water are hot the valve closes.
Watts Water Technologies produces a wide range of steam traps including
  • Watts Thermostatic Radiator Steam Traps
  • Float & Thermostatic Steam Traps
  • Watts Inverted Bucket Steam Traps
  • Watts Open Float & Thermostatic Steam Traps
  • Watts Thermodynamic Steam Traps
Watt Float Type Steam Trap This air vent on this steam trap is open when the system is cool - at the start of a heating cycle - allowing large volumes of air to discharge into the condensate return piping.
The float in this trap is closed and stays closed from start-up and while steam is in the trap body.
When hot condensate accumulates in the trap body the float lifts, closing the valve head and the trap. This product is intended to continuously discharge condensate in modulating conditions and is used on heat exchangers, air handling coils, and steam MAIN DRIP stations.
Watts Thermodynamic Steam Trap Watts ThermodynaThermostatic steam traps such as this Watts unit are used as high pressure steam main distribution line traps in the 75-600 psi range (and so won't appear on common low pressure residential steam heating systems).
At the start of a heating cycle the trap is open to discharge into the condensate line. As hot condensate "flashes to steam" as it passes through the trap body the valve closes and stays closed until the flash steam condenses.
Watts Open Float Thermostat Steam Trap Watts open float steam traps are used on low and medium pressure steam systems on the MAIN DRIP trap and also on heat exchangers, air handler coils, and steam process applications.
Watts explains the valve operation in four steps:
  • Condensate fills the trap until it overflows into float. When the weight of the condensate overcomes the buoyancy of the float, the float begins to drop independent of the float valve head
  • The float continues to drop until the collar at the bottom of the valve stem engages the internal stop. At this impact point, the float falls to the bottom of the trap snapping the valve open.
  • Condensate travels up the discharge tube, through the orifice and out the outlet port. The float will remain at the bottom with valve fully open so long as there is sufficient condensate entering the trap
  • As the discharge drains the float, buoyancy returns and the float begins to rise. The valve head is snapped closed into the valve seat by the velocity of the discharging condensate. - Watts Water Technologies (2014)
    Watts Inverted Bucket Steam Trap This inverted bucket trap used on steam systems must be manually primed at start up to create a water seal around the inverted bucket that allows this trap to operate.
    At start of a heating cycle the trap is open allowing air and condensate to enter the steam trap body. Air is discharged through a vent at the top of the device (see INVERTED BUCKET STEAM TRAP OPERATION).
    When steam enters the body of this inverted bucket steam trap the buoyancy of steam lifts the bucked, closing the valve in the trap head, closing the air vent.
    When condensate accumulates in the bucket trap the bucket falls, opening the air valve and also allowing condensate to drain into the condensate return line.
    These bucket traps are used as MAIN DRIP traps at pressures up to 250 psi and also on some steam systems where minimal air venting is acceptable.
    Watson McDaniel Watson W1031 Series Bucket Steam Trap Watson @1031-13-150 W103113150 Bucket Steam Trap, also appears painted blue as in model shown below
    3/4" NPT
    150 PSI
    Watson McDaniel Inverted Bucket Steam Trap Series 1038 Inverted Bucket Steam Trap

    Note: varying models of most of these steam traps accommodate a wide range of pipe sizes and fittings in both female and male NPT threads. Prices also vary widely depending on application, brand, model, and also used, refurbished, or new.

    The steam traps shown in these identification photos are only representative examples. You will want to consult the manufacturer, the manufacturer's parts catalog, or your heating equipment supplier to be sure of selecting the proper steam trap for your application. See STEAM TRAP MANUFACTURERS for a list of suppliers and steam trap supply contact information.

         การให้คำแนะนำเกี่ยวกับอุปกรณ์สตีมบอยเลอร์ (Steam Boiler) เพื่อความปลอดภัยในการทำงานและเพิ่มประสิทธิภาพของอุปกรณ์ ยินดีให้คำปรึกษาโดยผู้เชี่ยวชาญและรับข้อมูลเพิ่มเติมเกี่ยวกับบริการตรวจสอบหม้อต้มไอน้ำ (Boiler) ได้ที่


    (สวนอุตสาหกรรมโรจนะ อยุธยา) หมู่ 5 ถนน โรจนะ ตำบล คานหาม อำเภออุทัย จังหวัดพระนครศรีอยุธยา 13210
    เบอร์โรงงาน : อีเมล์ :