20929 Bridge Street, Southfield, MI 48033 4121 Brockton Drive SE, Grand Rapids, MI 49512 6200 Baron Drive, Bridgeport, MI 48722 6910 Treeline Drive, Suite A, Brecksville, OH 44141 Phone: (800) 589-6120 - Fax: (248) 354-3710 www.deppmann.com Serving the industry since 1927 March 9, 2009 ~ This week we look at the strainers in a steam system: Normally strainers are placed before control valves, on the steam side of the system, and before traps and condensate pumps on the condensate side of the system. While steam is generally cleaner than condensate, even small amounts of dirt in control valves can cause major issues. Dirt can keep control valves from closing, and even small particles of dirt can accumulate and plug up ¼” sensing lines around controls and pressure reducing valves. In condensate systems the concern is less about dirt and more about particles of rust or flakes of steel pipe becoming loose due to the aggressive nature of the condensate. (CO2 in the steam becomes carbonic acid when the condensate starts to cool) If fine mesh strainers are installed in the condensate piping system they may clog up quicker causing more maintenance and possible operational issues if they are not maintained properly. Mesh, Perf, and Diameters; what does it all mean? In the world of strainers we use three terms to describe the opening sizes of the screen. Mesh screens are normally the finest. A 20 mesh screen has 20 openings every inch of screen. Perf is short for perforation and refers to the size of the hole in the screen. A .062 perf screen has .062” holes or 1/16” holes. Diameter is a term sometimes used instead of perf. There are standard strainer screens and optional strainers screens available. For steam systems, we recommend you specify 20 mesh screens for strainers up to 2”, .045 perf from 2-1/2” to 6”, and .062 perf above 6”. For condensate systems we suggest .045 perf up to 2” and .125 perf above 2”. Please note that this type of specification will result in longer lead times than the standard off the shelf strainers. You may ask why we change the size of the hole in small pipe versus larger pipe when it is the same steam. The balancing act is to attempt to avoid too much maintenance while still protecting the traps and valves. As traps and control valves get larger, so does the orifice size. If we put fine mesh strainers throughout the system, they will plug more frequently and increase the number of times maintenance must clean them. For these reasons the size of the hole changes with the size of the pipe. We offer a variety of steam and condensate strainers from Metraflex and ITT Hoffman! Disclaimer: R. L. Deppmann and it’s affiliates can not be held liable for issues caused by use of the information on this page. While the information comes from many years of experience and can be a valuable tool, it may not take into account special circumstances in your system and we therefore can not take responsibility for actions that result from this information. Please feel free to contact us if you do have any questions.