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Jerguson Model 56 Tubular Valves

Offset union bonnet - Renewable seat - Forged body
Model 56 Tubular ValvesThe simplest and least costly method of liquid level indication is the tubular gage glass. Two slightly different designs are available.  Both are simply transparent vertical tubes with their lowest visible point connected to the tank or boiler at the lowest level of interest. The top of the glass may be open to the atmosphere if the tank is open or to the unfilled part of a closed vessel above or at the highest level permitted. Isolating valves are placed above and below the gage glass connections.

One choice is a gage glass with slow closing valves and the second choice are valves with quick closing type where a one quarter turn of the valve spindle will change the valve from the fully open to the fully closed position. The valve spindles are fitted with levers to which chains may be attached in order to operate the valves from ground level if the vessel is located at a higher position. Drain valves or cocks may also be installed below the gage glass to remove any solid material that may collect.

Since many tanks and pressurized vessels are not under continuous supervision, a broken gage glass may allow a large amount of fluids to escape. To prevent this, the lower valve on the gage glass is often equipped with a safety shutoff device consisting of a stainless steel ball which closes off the fluid passage when the glass breaks. One disadvantage of this type of safety device is that it requires more maintenance.

Under normal conditions, the steel ball remains in the recess in front of the valve seat. However, when the gage glass breaks, the sudden rush of fluid through the valve will force the ball against the valve opening. This shuts off the flow out of the broken glass.

The gage glass is usually surrounded by a number of metal rods or transparent shield to protect the glass from breakage and the operator from flying particles in case the gage glass shatters.

The use of tubular gage glasses is limited to lower pressures and temperatures, and restricted to non-toxic and non-hazardous material. Tubular gage glasses should not exceed 750 mm in length. If the level range to be observed exceeds this length, then two or more gage glasses should be installed so that they overlap.

Standard Features:
  1. 3/4" screwed inlet by 3/4" tubular glass by 1/2" drain.
  2. Renewable regrindable stainless steel seat.
  3. Ballcheck of stainless steel shut-off flow in event of tube breakage.
  4. Stainless steel trim.
  5. Offset bodies to permit the swabbing of glass by removing plugs from vent and drain.
Other Notable Features:
(1). Union tailpiece for ease of assembly.
(2). Sleeve construction to allow for:
(2A). quick closing - 90° from full open to tight.
(2B). to allow for backseating stem to protect packing.
(3). Valves can be used with heavy-duty plastic protector or 4 guard rods.
Roughing Dimensions:
Rough dimensions: to determine the following, deduct from center to center dimensions -
  • For approximate visible glass deduct 4-5/8"
  • For length of tubular glass deduct 1-3/8"
  • For length of guard rods deduct 1-1/8"
 Teflon Packing Model 56 Part No.
Stem Packing (molded) G130
Stem Packing (string) G244
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