DFT: Check Valves:

PDC® Flanged Check Valve

The DFT® Model PDC® Silent Check Valve is specially designed for use on the discharge side of reciprocating air or gas compressors.

The PDC® Silent Check Valve includes a pulse damping chamber to maintain the disc in the open position during the momentary reductions in flow associated with each cycle of a reciprocating compressor and to protect against premature seat wear.

Documentation:
Product Specifications
(143KB PDF)

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PDC Flanged Check Valve

Pulse-damped design
Modulating “air” or “gas” applications:
- Discharge of reciprocating air/gas compressors
- Self sizing accommodates varying flows without chattering
Meets API 6D
ASME B16.10 Face-to-Face dim
One-piece body
Spring-assisted silent closing
2” to 20” Line size
Stainless steel trim

PDC FLANGED CHECK VALVE SPECIFICATIONS
Class		150 RF	300 RF	600 RF	900 RF	1500 RF
2"	Dim A	8	10.5	11.5	14.5	14.5
	Dim B	6	6.5	6.5	8.5	8.5
	Weight	20	27	35	65	65
	Cv	62	62	62	55	55
	CP	0.41	0.49	0.41	0.35	0.35
3"	Dim A	9.5	12.5	14	15	18.5
	Dim B	7.5	8.25	8.25	9.5	10.5
	Weight	40	50	58	84	171
	Cv	148	148	142	118	118
	CP	0.62	0.62	0.66	0.78	0.78
4"	Dim A	11.5	14	17	18	*
	Dim B	9	10	10.75	11.5	*
	Weight	64	82	117	144	*
	Cv	255	255	255	224	*
	CP	0.68	0.68	0.31	0.82	*
6"	Dim A	14	17.5	22	24	*
	Dim B	11	12.5	14	15	*
	Weight	94	149	272	322	*
	Cv	660	660	660	567	*
	CP	0.51	0.51	0.49	0.63	*
8"	Dim A	19.5	21	26	29	*
	Dim B	13.5	15	16.5	18.5	*
	Weight	158	293	450	575	*
	Cv	1005	1005	1005	740	*
	CP	0.66	0.66	0.42	0.6	*
10"	Dim A	24.5	24.5	31	*	*
	Dim B	16	17.5	20	*	*
	Weight	260	452	740	*	*
	Cv	1610	1580	1540	*	*
	CP	0.5	0.38	0.46	*	*
12"	Dim A	27.5	28	33	38	44.5
	Dim B	19	20.5	22	24	26.5
	Weight	445	673	1068	1940	2590
	Cv	2300	2300	2300	1990	1590
	CP	0.29	0.29	0.29	0.7	0.7

The DFT® PDC Flanged Check Valve is a silent, non-slam check valve specially designed for use on the discharge side of reciprocating air or gas compressors.
The valve includes a pulse-damping chamber to maintain the disc in the open position during the momentary reductions in flow associated with each cycle of a reciprocating compressor and to protect against premature seat wear.

Materials of Construction:
Component	Carbon Steel Body	Stainless Steel Body
Body	A216 Grade WCB	A351 CF8M
Disc	A351 CF8M	A351 CF8M
Seat	A351 CF8M	A351 CF8M
Spring	A313 316 (450°F max.)	A313 316 (450°F max.)
Spring for ball check	Inconel® X-750	Inconel® X-750
Disc Guide	A479 316	A479 316
Bushing	Rulon®	Rulon®
Seal Ring	Teflon®/Hastelloy® C276	Teflon®/Hastelloy® C276
Spring Retainer - Ball Check	A479 316	A479 316
Guide Ring	Teflon®	Teflon®
Ball Check	440C SS	440C SS
Orifice Plug	A479 316	A479 316

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.