Valve Industry Knowledge Base

Flexi-Hinge Check Valves

FAQ

Frequently Asked Questions

Please review the list of frequently asked questions and click the link to jump to the answer. If your question is not shown, please contact us so that we may furnish an answer for you. For further information regarding valve terminology, please consult our Valve Glossary.

1. How does a Flexi-Hinge valve work?
2. What makes Flexi-Hinge design superior?
3. What causes pressure Loss?
4. What is Cv (also called C sub v)?
5. What are the key features of a Flexi-Hinge check valve?
6. What is water hammer?
7. What are the min/max operating temperatures and pressures?
8. What seal materials are available?
9. What body styles are available?
10. Do you manufacture Specials?
11. What do you stock?
12. What internal seal material should I choose?
 
 
 



1. How does a Flexi-Hinge® valve work? 

The Flexi-Hinge® incorporates a fully ported, double door, seatless design. The valve plates and body are match machined to allow the valve to seat against the valve body I.D. at a set angle. Additionally the seal material serves two functions. One is as the hinge mechanism. The other provides for the bubble tight sealing characteristics.

Cracking pressure is 0.1 P.S.I. A full bubble tight seal is achieved with 0.5 P.S.I. of back pressure. The Flexi-Hinge® valve line has the highest Cv value of any known style check valve.

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2. What makes Flexi-Hinge® design superior? 

The Flexi-Hinge® design engineer’s have, in effect, designed an anomaly: a seated seatless style check valve.  Our Flexi-Hinge® design offers the best of both designs.  The center seat design allows for higher pressure ratings than competitive seatless designs. No circumferential seat provides more flow area resulting in higher flow potential and lower pressure losses. Our self-actuating design eliminates the need for a spring in horizontal or vertical up valve orientations resulting in improved performance, longer life-expectancy and lower costs.  Put it all together with large inventories, sizes from 1” thru 24” and friendly customer service, you’ll agree that the Flexi-Hinge® Next Generation Design is superior.

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3. What causes pressure Loss?  

There is a loss of pressure when a liquid or gas flows through a pipe because energy is required to overcome the viscous or frictional forces exerted by the walls of the pipe on the moving fluid. In addition to energy being lost due to the frictional forces, the flow also loses energy (or pressure) as it goes through fittings such as valves, elbows, contractions and expansions. This loss in pressure is mainly due to the fact that flow separates locally as it moves through such fittings. Separation is accompanied by viscous dissipation of energy.

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4. What is Cv, also called C sub v? 

By definition Cv is the calculation of a valve’s flow potential with 1 PSI of pressure loss.  The 1 PSI of pressure loss is a constant that can be used to compare the flow potential of different valve styles.  The higher the Cv number the more efficient the valve is, thus providing the lowest pressure loss. 

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5. What are the key features of a Flexi-Hinge check valve?

Some of the key features are pressure rating have been increased to 200 PSI. Flow areas have been maximized allowing for the highest Cv ratings. The machined support shelf along the center post locks the valve plates into position. This effectively eliminates failures caused by the valve plates cutting into the seal as the competitor's products do. The machined radius on the center post allows the valve to operate without a costly spring. The Teflon coated stop helps reduce noise. Finally, valve materials have been standardized to lower costs.

6. What is water hammer?  

Water hammer is the result of pressure fluctuations that develop in a pipe when flow is changed quickly. This can be caused by either a valve closing quickly or by a pump starting quickly. The Flexi-Hinge® check valve products may have some dampening effect when checking flow. The operation of the valve is as follows; when flow is stopped the valve will quickly begin to close, but will not close completely. A back pressure of at least ½ PSI is required to complete the bubble tight closure. This action should help reduce some of the sudden pressure fluctuations caused by a quick stoppage or reversal of flow. The valve will have little if any effect on reducing water hammer caused by sudden pump action. However, our stop which is Teflon coated will help reduce noise and secondary vibrations caused by a quick acting pump.

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7. What are the min/max operating temperatures and pressures?

The complete line of Flexi-Hinge® Check Valves are rated at 200 P.S.I. (maximum pressure). Depending on the selected seal materials operating temperature ranges from   -1000° F. to +5000° F. for intermittent service.

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8. What seal materials are available? 

The standard available seals are Buna-N, EPDM, Viton and Silicone. Additional specialty seals are available.

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9. What body styles are available?

We offer most standard pipeline connections. We have a Male Threaded End in styles 502M and 517M. We offer 150# flanged ends in styles, 503, 581 and 517. Our Victaulic grooved style is 513 and our Plain End connections are style 514. We offer the 518 Wafer series.

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10. Do you manufacture Specials?

Flexi-Hinge® Valve Co offers complete in-house engineering and fabrication capabilities. Size or materials are no object. We can handle exotic materials as well as higher or lower pressure applications. Just let us know your service parameters and we will take it from there.

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11. What do you stock?

We stock from 1" through 24" standard pipeline connections in Erie, Pennsylvania. We offer bodies in cast iron or steel, aluminum or 316 stainless steel. Internals are offered in either aluminum or 316 stainless steel. Next Day or even Same Day delivery is possible when needed.

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12. What internal seal material should I choose? 

The standard available seals are Buna-N, EPDM, Viton and Silicone. Any of these standard materials may be appropriate for your application. However, not all seal materials will handle all chemicals being transported. Please consult the Materials Selector or contact us directly to assist you in your seal selection.

 

 

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