Chemline Plastics has released its SB Series back pressure/relief valves in solid plastics and stainless steel. They are designed for chemical dosing lines 1/4in to 4in. They offer opening and adjustable relief pressures of 3 to 150psi. The advanced hydraulic design offers high flow rates, low hysteresis, and low overpressure to fully open. The new “Chem-Flare” end connections provide a long term zero leakage solution for sodium hypochlorite services. SB17 is the compact model and is for 1/4in to 1/2in tubing, while the SB12 is available for pipe sizes 1/2in to 4in. The same valve offers both back pressure and relief functions. For relief the valve is installed on the branch of a tee. The Chemline SB Series back pressure/relief valve has two functions. As a back pressure valve, installed in-line downstream of a pump, the back pressure below the metering pump is maintained. When installed in the branch of a tee it is a pressure relief valve. The valve stays closed until inlet pressure reaches the set pressure, which is adjusted by turning the spring tensioning bolt. Inlet pressure acts on the Teflon® control diaphragm opening the valve, allowing excess pressure to flow downwards through the orifice. The SB10/11 Series is very sensitive to pressure changes and requires low overpressure to fully open.