Armstrong LS & MS Series ultra-capacity float and thermostatic steam traps are designed for heavy-duty industrial applications where highly efficient, uninterrupted service is essential. The simple yet rugged cast steel construction offers long, trouble-free service, with capacities reaching up to 280,000 lb/hr (127,000 kg/hr) and pressures up to 450 psig (31 bar).

All floats, valves and seats, and lever mechanisms are constructed of stainless steel. The integral thermostatic air vent is a balanced-pressure phosphor bronze bellows caged in stainless steel. This balanced-pressure air vent will respond to the pressure-temperature curve of steam at any pressure from zero to 250 psig (17 bar). Thus—up to 250 psig (17 bar)—air is vented at slightly below steam temperature.

Maximum Operating Conditions

Maximum allowable pressure (vessel design):

• Model LS: 450 psig @ 650°F (31 bar @ 343°C)
• Model MS: 450 psig @ 650°F (31 bar @ 343°C)

Maximum operating pressure:

Model	Maximum Operating Pressure
30-LS	30 psig (2 bar) saturated steam
100-LS	100 psig (7 bar) saturated steam
150-LS	150 psig (10 bar) saturated steam
250-LS	250 psig (17 bar) saturated steam
250-MS	250 psig (17 bar) saturated steam
450-LS	450 psig (31 bar) saturated steam
450-MS	450 psig (31 bar) saturated steam

Maximum operating temperature bellows: 422°F (217°C)

NOTE

For pressures above 250 psig (17 bar), the thermostatic vent should be removed and only a CC (Condensate Controller) or LD (Liquid Drainer) version should be used.

Materials

Part	Material
Body and cap	ASTM A216 WCB Cast Steel
Internals	All stainless steel—304
Valve(s) and seat(s)	Stainless steel
Drain plug	Carbon steel
Thermostatic air vent	Stainless steel and bronze with phosphor bronze bellows, caged in stainless steel

Dimensions and Weights

Trap Series	LS & MS	LS & MS	LS & MS
Pipe Connection (in / mm)	2" / 50 mm	2-1/2" / 65 mm	3" / 80 mm*
"B" Height (mm)	508	508	508
"C" Width (mm)	387	387	387
"D" Bottom to CL (mm)	106	106	106
"H" Length (mm)	508	508	508
"M" CL to CL (mm)	287	287	287
Weight (screwed & SW) (kg)	131.5	131.5	131.5
Weight (flanged PN40) (kg)	137.5	140.5	143.5

*MS Series available in 3" (80 mm) only.

Options and Special Configurations

• Integral vacuum breaker (VB): 150 psig (10 bar) maximum. Add suffix VB to model number.
• Liquid Drainer (LD): No internal thermostatic air vent for liquid drainer service. Add suffix LD to model number. Developed to meet very large capacity needs in draining water and other liquids from air or other gases under pressure. To prevent air or gas binding, the access port in the top of the body serves as a back vent connection to the equipment being drained.
• Condensate Controller (CC): Integral flash release for syphon drainage service. Add suffix CC to model number. Developed especially to meet very large capacity needs in applications where condensate must be lifted from the drain point to the trap. Equipped with a fixed, restricted orifice near the top of the body to bleed off flash steam and air.
• Armored gauge glass (GG): 250 psig @ 424°F (17 bar @ 218°C).
• Floor mounting bracket: LS and MS Series available with floor mounting bracket.

Capacities

LS Series Capacity

MS Series Capacity

Installation Notes

Under conditions where the load may approach the maximum capacity of the trap, it is recommended that the size of the discharge line be increased one size as close to the trap cap as is practical.

When LS and MS Series units are used in severe service conditions or at pressures exceeding 30 psig (2 bar), use an anchoring bracket or other supportive measures to minimize stress on piping.

WARM-UP PROCEDURE

Ultra-Capacity LS and MS Series units MUST BE WARMED UP in the proper sequence and gradually. Recommended warm-up rate not to exceed 100°F (55°C) per 8 minutes. If warm up is not completed in the proper time and sequence, serious and costly damage could occur to heat exchange equipment, piping, fittings, and valves as a result of thermal stress and/or water hammer.

VACUUM BREAKER

Many times, condensate will be retained ahead of steam traps because of the presence of a vacuum. To break a vacuum, air must be introduced into the system by means of a vacuum breaker. For maximum protection against freezing and water hammer in heating coils under modulated control, vacuum breakers are recommended in conjunction with freeze protection devices.