Page 142 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

SOLID-LIQUID SEPARATION AND INTERCEPTORS

3.10 CHAPTER THREE

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FIGURE 3.3 Pressure drop through Y-type stainers.

second with a finer mesh or smaller openings for small particles. This would prevent the
loading up and frequent cleaning of the strainer in a one-strainer system by spreading out
the cleaning load to two strainers.
There are a number of methods used to divert flow between strainers for cleaning. The
most common is a multiport plug valve. For large pipe, the plug valve may get too large. For
larger strainers, sliding gate valves that have synchronized discs operated by handwheels
to divert flow are often used. Another method is to use synchronized butterfly valves. The
actual method selected depends on the available friction loss, available room, and cost.
Basket strainers are usually large units with a high initial cost. In general, Y strainers
have a lower initial cost for the same size unit, smaller dirt-holding capacity, and larger
friction loss because of their smaller bodies. It is good practice to allow higher pressure
safety margins due to the possibility that the strainers will be placed in a position to receive
water hammer shocks and water slugs. There must be enough room around the unit(s) for
the necessary frequent cleaning and laydown of the basket.

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