Steam Gun Set

2.9.5.2 Design steam and condensate piping with loops, bends and offsets to

allow for thermal expansion and keep stresses within the allowable limits of

the piping material. Avoid using expansion joints or ball joints, if

possible.

2.9.5.3 Provide roller-type pipe supports where significant horizontal pipe

movement will occur due to thermal expansion and spring-type supports where

significant vertical movement will occur.

2.9.5.4 The minimum pipe size shall be 25.mm (1-inch) in horizontal runs and

20 mm (3/4-inch) in vertical runs; make any pipe size reduction necessary at

the equipment. Long horizontal pipelines shall not be run at the floor.

Wherever possible, provide up feed connections through the floor to the

equipment.

2.9.5.5 For large steam service, such as the low pressure system for

absorbers, provide small globe type warm-up valve, located for convenient

operation, to by-pass the main shut-off valve. By-pass valves shall be shown

and specified for gate valves 102 mm (4 inches) and larger in steam lines.

2.9.6 STEAM GUN SET

2.9.6.1 A steam gun set (steam, water, detergent) shall be provided in the

following areas per VA Standard Detail 15705-21.

(a) Trash room or trash compaction room

(b) Manual cart wash, Dietetics

(c) Manual cart wash, Supply, Processing & Distribution (SPD)

2.9.7 STEAM TRAPS

2.9.7.1 Steam traps on domestic hot water heaters, heating coils and other

steam equipment utilizing modulating control valves shall be closed float-

thermostatic type with operating pressure range suitable for the maximum

steam supply pressure. Trap capacities shall be calculated and shown on the

drawings in pounds per hour at one-quarter psig pressure differential across

the trap provided the inlet of the traps are 12 inches below the condensate

outlet of the equipment. The allowable pressure drop across the trap may be

increased if the trap leg is allowed to increase. Steam traps shall be sized

based on the maximum condensing rate of the equipment they serve times a

safety factor of 1-1/2 or 2. Consult the manufacturers of steam traps.

2.9.7.2 Steam traps on steam line drip points shall be inverted bucket type,

with bi-metallic thermal element for air removal, with working pressure range

suitable for the maximum line pressure. Trap capacities shall be shown on the

drawings in pounds per hour at a specified pressure differential across the

trap as follows:

(a) For steam lines that will be in operation continuously, with infrequent

shut downs, drip traps shall be sized for the line radiation loss, in pounds

per hour, times three. The trap pressure differential shall be about 80

percent of the line operating pressure.

(b) For steam lines subjected to frequent warm-up, the trap capacity shall be

the amount of steam condensed when the line is warmed up to operating

HVAC DESIGN MANUAL

2-23

HVAC SYSTEMS AND EQUIPMENT