Thermostatic Radiator Traps - The Sterlco Smart Trap

In a trap which is cold, or which is full of condensate below the boiling point, the Sterlco thermostat remains compressed because of its internal vacuum. The trap is open and condensate flows out.

Whenever live steam strikes the bellows, the water inside the thermostat starts to vaporize or boil. As soon as the steam pressure inside the thermostat becomes almost equal to the steam pressure surrounding the thermostat, the spring action of the bellows causes it to extend itself and close the trap. Because the thermostat is filled with pure water, the relationship of inside and outside pressures is always the same. This trap will always pass condensate and hold back steam in spite of any variations in steam pressure.

If the thermostat is damaged, the vacuum inside will be lost and the trap will remain closed whether it is hot or cold. The location of the trouble will be easy to find because the radiator will be cold. Meanwhile. no steam is wasted.

Constuction:

Trap bodies. covers. union nuts and nipples are close grained red brass castings. Accurate machining assures steam-tight fit and complete interchangeability of parts. Sterlco"low pressure traps, except 715-A, have valve cones of long-wearing tobin bronze and seats of brass. All others have stainless steel cones and seats for maximum resistance to high temperatures and abrasion. Stainless steel cones and seats are available for 112" and 314" LP traps.

Features:

Bellows convolutions are formed under extremely high hydraulic pressure.
Smooth bellows surfaces means no tool marks where wear or corrosion can start.
Multiple convolutions provide free travel of the valve cone. There is no danger of failures due to excessive bellows flexing.
Vacuum charged ... not charged at atmospheric pressure. The trap will close immediately if damaged.

The Sterlco Smart Trap:

Will operate efficiently regardless of steam pressure variation. All thermostats and seats are replaceable without shimming or adjustment. Every trap is thoroughly tested. Components are inspected and tested during manufacture; completed traps undergo complete operating tests before shipment.

Angle Pattern - 750 Series for low pressure; M-7 Series for medium pressure; 8 Series for high pressure.
Straightwy Pattern - Provides minimum loss of height on horizontal piping.
Vertical Pattern - 780 Series for vertical piping and convectors.
Corner Pattern - 770 Series for low pressure heating. In right hand and left hand styles for convient installation.

Dimensions and Capacities:

Pressure

Inlet and Outlet

Dimensions

Capacity in Sq. Ft. E.D.R. at

Rating

Size (Am. Std.

Model

Body Style

Pressure Differentials Indicated (in LBS.)

Lbs./Sq. In.

Pipe Thd.)

114

112

0-25 Low

Pressure

1/2"

750-A

Angle

3-1/4*

1-1/4

120

165

235

370

530

640

770-R

R.H.Comer

3-1/4*

3/8

1-5/8

770-L

L.H. Corner

3-1/4*

3/8

1-5/8

770-S

Straightway

4-7/8*

3/8

780-V

Vertical

3/4"

753-A

Angle

3-1/8*

1-1/4

165

230

330

465

730

1050

1300

773-S

Straightway

5-1/4*

3/8

715-A

Angle

3-1/4*

1-5/8

290

1 410

1 580

1 810

1 1280

1840

2300

Note: Above ratings are in accordance with the standards of the Steam Heating Equipment Manufacturers Association. Since actual test capacities are from two to four times these ratings, traps may be selected directly from the table for the lowest pressure differential expected.

Pressure	Inlet and Outlet			Dimensions		Capacity in Sq. Ft. E.D.R. at
Rating	Size (Am. Std.	Model	Body Style			Pressure Differentials Indicated (in LBS.)
Lbs.ISq. In.	Pipe Thd.)			A	B	5	10	15	25	50	65	75	100	125
0-75 Med. Pressure	1/2"	M-750-A	Angle	3114*	1114	525	780	985	1340	2020	2175	-	-	-
	3/4"	M-753-A		3118*	1114	585	1040	1405	1670	2390	2490	-	-	-
	1"	M-715-A		3114	1518	710	1300	1900	2715	4130	4690	-	-	-
0-125 High Pressure	1-1/2"	850-A	Angle	3114*	1114	400	640	935	1240	1750	1965	2080	2280	2400
	1-3/4"	853-A		23/4	1114	510	900	1400	1900	2500	2720	2850	3100	3340
	1"	812-A		3114	1518	710	1300	1900	2715	4130	4690	4940	5385	5720

* Available with tail pieces to reduce or increase "A" dimension by 318 inch.

Sterlco@ thermostatic radiator traps accurately and efficiently free radiators of air and condensate... without allowing steam to be wasted into retums. They are especially effective on vacuum heating systems. Their simple design and rugged construction assure long, dependable service.