Check valves are available in numerous types, styles and shapes. Generally a valve manufacturer builds only one type of check valve. APCO builds six (6) types and fourteen (14) styles. We offer the consulting engineer open, objective and unbiased information about a broad range of check valves; their proper selection and application. The purpose of this treatise is to collect and condense the many desirable and undesirable features of the most common type checks into a single source. With this single source of information we will simplify the design engineer's check valve selection and make this selection accurate and compatible with the application intended.   Compact, in-line mounted, instantaneous shutoff against reverse flow, low forward pressure opening. ASCO Valve is the worldwide leader in the design and manufacture of quality solenoid valves. ASCO products are designed to control the flow of air, gas, water, oil and steam. Our heritage of innovation has resulted in an extensive line of ASCO products that range from two position on/off valves to entire flow control solutions designed to meet requirements of thousands of customers. Whether you need a minor modification of a core product or a complete flow control solution, we can help.   The Chemline SC Series Swing Check Valve is the heaviest duty solid plastic non-return valve available. The strong one piece flanged body is suitable for installation in any type of piping, horizontally or vertically. A large choice of body materials and seals including PVDF and Teflon® allow its use in the most aggressive chemical services. Pressure drop is low due to full flow design. The Chemline WP Series Wafer Check Valve is a non-return valve ideal for limited space installations. These valves are economical and available for large pipe sizes, 2" to 12" and larger†. They are available in two versions – with or without disc springs. The spring adds force for faster, more silent closing.   A check valve is useful for preventing sudden backflow of pressurized fluid. Parker C Series Check Valves provide unidirectional control of liquids and gases. A choice of eight valve crack pressure springs from 1/3 psig (2.3 kPa) to 100 psig (689 kPa) are available. The unique molded seat design is resistant to blow-out and is available in Nitrile, Fluorocarbon, Ethylene Propylene, and Neoprene to meet the performance needs of any system. A variety of US Customary and SI port connections, including CPI™ and A-LOK® compression, and female and male NPT are available.   The Sure Flow Check wafer check valve is a precision engineered, fully developed product at the forefront of pipe system technology. Sure Flow Check can be installed with confidence into offshore or onshore pipeline systems on product or service lines, wherever non-return protection is required. Manufactured to meet API specifications, Sure Flow Check meets all the key criteria and in the vitally important area of comparative weights is actually lighter than other wafer check valves. Sure Flow Check offers other operational benefits. It is light, tight, strong, compact and cost effective. Sure Flow Check is a precision engineered dual plate wafer check valve. It has been designed specifically for its environment and its duty. Every component has been carefully chosen only after matching its performance requirements with value analysis criteria.   Trueline Valve Corporation is a leading manufacturer of industrial valves since 1981. Our exceptional growth is a result of our strategic plan which is driven by continuous customer feedback. Trueline is a great valve company.   Wilkins, a Zurn Company, has been supplying quality water control products to the marketplace since 1906. Products include backflow preventers, pressure regulators, and a variety of other support products. Originally based out of Mr. James Wilkins’ 200 square foot garage in Los Angeles, Wilkins has grown from this humble beginning to a 162,000 square foot manufacturing facility in Paso Robles, CA, with over 200 employees producing high quality water control products, and is now part of the Jacuzzi Brands, Inc. family of companies. We would like to thank all of our customers that enjoy and appreciate our dedication to innovation, quality, and customer service – the foundation of our success over the last 100 years. This dedication to the customer is our foundation and we look forward to serving you in our second century and beyond!