DFT: Check Valves:

GLC® Flanged Check Valve

The DFT® Model GLC® Silent Check Valve is a spring-assisted, center guided, in-line, flanged check valve that provides reliable, low maintenance service for a wide range of fluids and pressure/temperature combinations.
The DFT® GLC® check valve has the advantage of minimum pressure loss with silent, non-slam operation.
Short Face-to-Face dimensions.
Horizontal or vertical installation.
One piece body.

Documentation:
Product Specifications
(146KB PDF)

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GLC Check Valve

“Short” Face-to-Face dimensions
API 6FD Fire Test
- ASME Class 150 and 300
- 2” to 24”
Standard body materials:
- A216 Grade WCB carbon steel
- A351 CF8M stainless steel
Optional body materials:
- Alloy 20
- Duplex SS
- Hastelloy®
- Monel®
- Nickel-Aluminum Bronze
One-piece body

GLC FLANGED CHECK VALVE SPECIFICATIONS
Class		150 RF	300 RF	600 RF	900 RF	1500 RF	2500 RF
1"	Dim A	4.5	4.75	5.25	*	*	*
	Dim B	4.25	4.88	4.88	*	*	*
	Weight	7	9	11	*	*	*
	Cv	17	19	17	*	*	*
	CP	0.85	0.85	0.85	*	*	*
1-1/2"	Dim A	5.75	6	6.63	7.38	7.38	*
	Dim B	5	6.13	6.13	7	7	*
	Weight	13	17	19	30	30	*
	Cv	35	35	35	26	26	*
	CP	0.29	0.29	1.29	0.64	0.4	*
2"	Dim A	6.25	6.5	7.25	8.25	8.25	9.25
	Dim B	6	6.5	6.5	8.5	8.5	9.25
	Weight	17	23	25	56	56	77
	Cv	63	63	63	46	46	32
	CP	0.29	0.29	0.29	0.32	0.32	0.47
2-1/2"	Dim A	7	7.25	*	9	9	*
	Dim B	7	7.5	*	9.63	9.63	*
	Weight	31	41	*	78	78	*
	Cv	100	100	*	81	81	*
	CP	0.18	0.18	*	0.11	0.11	*
3"	Dim A	7.5	7.88	8.63	9.13	9.88	14
	Dim B	7.5	8.25	8.25	9.5	10.5	12
	Weight	33	46	57	87	110	218
	Cv	148	148	125	114	114	77
	CP	0.2	0.2	0.41	0.26	0.52	0.43
4"	Dim A	8.5	9.13	10.13	10.63	11.38	15.5
	Dim B	9	10	10.75	11.5	12.25	14
	Weight	55	71	115	127	164	332
	Cv	260	267	237	217	192	133
	CP	0.49	0.48	0.54	0.49	0.67	1.15
5"	Dim A	9.5	10.38	*	*	*	*
	Dim B	10	11	*	*	*	*
	Weight	72	89	*	*	*	*
	Cv	415	415	*	*	*	*
	CP	0.28	0.28	*	*	*	*
6"	Dim A	10	11	12.38	13	15.13	*
	Dim B	11	12.5	14	15	15.5	*
	Weight	93	139	175	264	405	*
	Cv	620	620	549	549	441	*
	CP	0.41	0.39	0.46	0.46	0.42	*
8"	Dim A	12	13	14.63	15.25	17.5	*
	Dim B	13.5	15	16.5	18.5	19	*
	Weight	172	232	332	396	670	*
	Cv	1030	933	933	851	742	*
	CP	0.41	0.45	0.45	0.5	0.55	*
10"	Dim A	14	15.38	17.13	17.63	23	*
	Dim B	16	17.5	20	21.5	23	*
	Weight	266	335	450	539	1281	*
	Cv	1630	1704	1620	1499	1231	*
	CP	0.55	0.52	0.35	0.64	0.53	*
12"	Dim A	18	19.5	21.25	*	44.5	*
	Dim B	19	20.5	22	*	26.5	*
	Weight	387	550	840	*	2550	*
	Cv	2370	2370	2272	*	1689	*
	CP	0.47	0.49	0.41	*	0.6	*
14"	Dim A	21	23	24	*	*	*
	Dim B	21	23	23.75	*	*	*
	Weight	456	724	975	*	*	*
	Cv	0.52	0.43	0.43	*	*	*
	CP	0.52	0.43	0.43	*	*	*
16"	Dim A	22.5	24	26	25.81	*	*
	Dim B	23.5	25.5	27	27.75	*	*
	Weight	700	898	1093	1940	*	*
	Cv	5100	5100	5100	4590	*	*
	CP	0.51	0.59	0.59	*	*	*
18"	Dim A	24	24	*	*	*	*
	Dim B	25	30.88	*	*	*	*
	Weight	753	1255	*	*	*	*
	Cv	6400	6400	*	*	*	*
	CP	0.59	0.59	*	*	*	*
20"	Dim A	24	24	35	*	*	*
	Dim B	27.5	30.5	37	*	*	*
	Weight	1292	1357	2625	*	*	*
	Cv	7700	7700	9828	*	*	*
	CP	0.49	0.55	0.59	*	*	*
24"	Dim A	28	28	29.33	*	*	*
	Dim B	32	36	37	*	*	*
	Weight	1571	2420	3470	*	*	*
	Cv	11100	10510	9850	*	*	*
	CP	0.44	0.46	0.57	*	*	*

The DFT® GLC Flanged Check Valve is a spring-assisted, center guided, non-slam check valve that provides reliable, low-maintenance service for a wide range of fluids and pressure/temperature combinations.
The valve consists of a body, seat, spring, disc with stem, guide bushing and gasket.
The DFT GLC check valve has the advantage of minimum pressure loss with silent operation.

Options:

Inconel® X-750 Spring
Custom sizing low flow
Stellite® trim
NACE

Soft seat
Severe service trim
RTJ Ends

Materials of Construction:
Component	Carbon Steel Body	Stainless Steel Body
Body	A216 Grade WCB	A351 CF8M
Disc/Stem Assembly	A351 CF8M/A479 316	A351 CF8M / A479 316
Seat	A351 CF8M	A351 CF8M
Spring	A313 316	A313 316
Bushing	A479 316	A479 316
Gasket	CFG/316 SS/Graphite

Check Valve Operation:

A check valve allows flow in one direction and automatically prevents back flow (reverse flow) when fluid in the line reverses direction. They are one of the few self-automated valves that do not require assistance to open and close.

Check valves are flow sensitive and rely on the line fluid to open and close. The internal disc allows flow to pass forward, which opens the valve. The disc begins closing the valve as forward flow decreases or is reversed, depending on the design. The function or purpose of a check valve is to prevent reverse flow.

Internal sealing of the check valve disc and seat relies on “reverse” line pressure as opposed to the mechanical force used for on/off valves. Because of this, allowable seat leakage rates are greater for check valves than with on/off valves.

Factors affecting check valve seat leakage include reverse pressure, medium, and what the seat material is made of, such as metal or elastomer. Metal sealing surfaces generally will allow some leakage while elastomers such as Buna-N and Viton provide bubble-tight shutoff (zero leakage).

The longest trouble-free service will come from valves sized for the application, not the line size, whereby the disc is stable against the internal stop in the open position or fully closed. When these conditions are met, no fluttering of the disc will occur (resulting in premature failure.)

Check valve internals are flow sensitive. If there is not enough flow disc movement occurs inside the valve resulting in wear, potential failure, and a higher pressure drop than calculated.

Typically, pressure drop is calculated based on the check valve being 100% open as with on/off valves. However, if the flow is not sufficient to achieve full opening, but instead, the check valve is only partially open, the pressure drop will be greater than calculated since the flow passage is restricted by the disc being in the flow path.

In this situation, a large rated Cv actually becomes detrimental to the check valve (unlike with on/off valves), resulting in fluttering of the disc and eventual failure.

Two of the most common problems with check valves are reverse flow and water hammer. In both situations, a fast-closing valve is desired.

When installing check valves, point the “flow arrow” in the direction of the flow to allow the valve to perform its function. The flow arrow can be found on the body or tag.