The Purpose of Liquid Control Strainers
Strainers help to protect meters from serious damage caused by burrs dislodged from new piping, pipe scale or foreign material. The initial cost of the strainer is good insurance against the cost of down time and replacement parts incurred from a damaged meter. A meter strainer installed on the inlet side is necessary even when a coarse strainer on the upstream side of the pump is included in the system. Strainers are not meant to be used as a system filter but as limited protection for the meter element itself.
How Liquid Controls Strainers Work
As a liquid product enters the strainer housing from the supply line, it is routed through the strainer basket. The strainer basket is a two-ply screen. The inner screen is made of fine mesh of either 20, 40, 80, 100, or 200 squares per inch. The outer screen works as a backing. It gives reinforcement and support to the fine mesh inner screen. Liquid passes through the strainer and into the inlet of the meter. Any debris that is larger than the mesh in the basket is trapped in the basket. THE STRAINER IS NOT A FILTER, and the size of the mesh in the basket selected will determine the particle size that can pass through the strainer. Basket mesh selection is generally based on maximum fluid viscosity at minimum ambient operating temperature.
Features
Liquid Controls markets a wide variety of strainers to fit most meters in terms of capacity, pipe size, working pressure and metallurgical compatibility. The design advantages of a Liquid Controls strainer include:
• Strainer baskets with an high open basket area-to-pipe area ratio, resulting in minimum restriction of flow and low pressure loss.
• Choice of 20, 40, 80, 100 or 200 mesh cadmium plated steel or stainless steel strainer baskets.
• Installation in a variety of positions that simplifies piping.
• Optional 45-degree accessory elbows for indexing strainer inlet positions other than right angle flow. Available for 2” F-7 Aluminum strainers only.
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Relieving Internal PressureAll internal pressure must be relieved to zero pressure before disassembly or inspection of the strainer, vapor eliminator, any valves in the system, the packing gland, and the front or rear covers. |
WARNING: Serious injury or death from fire or explosion could result in performing maintenance on an improperly depressurized and evacuated system. |
Relieving Internal Pressure Procedure for LPG and NH3 Meters Follow these steps:
1.Close the belly valve of the supply tank. 2.Close the valve on the vapor return line. 3.Close the manual valve in the supply line on the inlet side of the meter. If no manual valve exists on the inlet side, consult the truck manufacturer for procedures to depressurize the system. 4.Slowly open the valve/nozzle at the end of the supply line. 5.After product has bled off, close the valve/nozzle at the end of the supply line. 6.Slowly crack the fitting on top of the differential valve to relieve product pressure in the system. Product will drain from the meter system. 7.As product is bleeding from the differential valve, slowly reopen and close the valve/nozzle on the discharge line. Repeat this step until the product stops draining from the differential valve and discharge line valve/nozzle. 8.Leave the discharge line valve/nozzle open while working on the system. |
