Product Overview

GESTRA RK 76 series flanged wafer check valves (also known as non-return valves) are specifically designed to prevent backflow in pipelines, featuring a wafer-type construction that can be directly clamped between two flanges for convenient installation. The product is equipped with a spiral centering ring to ensure precise installation alignment. It supports two designs: with spring (installable in any position) and without spring (suitable only for vertical pipelines with upward flow). The valve is suitable for various media including liquids, gases, steam and corrosive fluids, with pressure ratings covering PN6 to PN40 and ASME Class125 to 300, widely used in industrial pipeline systems.

Technical Parameters

Pressure and Temperature Ratings

DIN/EN PN40 Conditions (Metal-to-metal seal)

Temperature (℃)	-10	20	50	100	150	200	250	300
Working pressure (barg)	40.0	40.0	40.0	38.1	34.2	30.2	28.0	25.8

ASME Class300 Conditions (Metal-to-metal seal)

Temperature (℃)	-10	20	50	100	150	200	250	300
Working pressure (barg)	49.6	49.6	48.1	42.2	38.5	35.7	33.4	31.6

Seat Characteristics

Disc Seal Material	Minimum Temperature (℃)	Maximum Temperature (℃)	Applicable Media	Leakage Class
Metal-to-metal	-10	300	Liquids, gases, steam	DIN EN 12266 Class D
PTFE	-190	250	Corrosive fluids	DIN EN 12266 Class D
EPDM	-40	150	Water, condensate, steam	DIN EN 12266 Class A
FPM	-25	200	Mineral oils, gases, air	DIN EN 12266 Class A

Cracking Pressure (Zero-flow pressure differential)

Nominal Port Size (DN)	Without Spring (X) (mbar)	With Spring (X) (mbar)	With Spring (V) (mbar)	With Spring (Y) (mbar)
15	2.5	10	7.5	5
20	2.5	10	7.5	5
25	2.5	10	7.5	5
32	3.5	12	8.5	5
40	4.0	13	9	5
50	4.5	14	9.5	5
65	5.0	15	10	5
80	5.5	16	10.5	5
100	6.5	18	11.5	5

Note: Special springs can be customized with cracking pressure ranges: DN15-50: 20-1000 mbar, DN65-80: 20-700 mbar, DN100: 20-500 mbar, additional charge applies.

Dimensions and Weight

Key Dimensions (Unit: mm)

Nominal Port Size (DN)	Nominal Port Size (inch)	Length (L)	Outer Diameter (∅D) (PN6-40)
15	½	16	45
20	¾	19	55
25	1	22	65
32	1¼	28	75
40	1½	31.5	85
50	2	40	98
65	2½	46	118
80	3	50	134
100	4	60	154

Note: Length (L) complies with EN 558 basic series 49 (equivalent to DIN 3202-3 series K4).

Weight Details

Nominal Port Size (DN)	15	20	25	32	40	50	65	80	100
Weight (kg)	0.18	0.30	0.45	0.70	0.90	1.50	2.10	3.40	5.20

Material Specifications

Component Name	DIN/EN Standard Material	ASME Standard Material	Material Category
Body, Seat, Guide ribs	1.4107	SA217 CA15	Chromium steel
Disc, Spring seat	1.4571	-	Stainless steel
Spring	-	Stainless steel	Stainless steel
Spiral centering ring	1.4310	-	Chromium steel

Optional Configurations

• Special spring: Cracking pressure 20-1000 mbar (limited by port size, additional charge)
• Seat material: EPDM/FPM/PTFE (default: metal-to-metal)
• Silicone-free design
• Oil-free and grease-free treatment
• Pickling and passivation treatment
• Orifice design
• Sealing gasket: EN 1092 Form B2, ASME RFS (smooth surface)

Installation and Usage Instructions

1. Installation position: Spring-equipped models can be installed at any angle; models without spring are suitable only for vertical pipelines with upward flow.
2. Alignment requirements: Ensure precise alignment between valve body and pipeline flanges through the spiral centering ring.
3. Minimum flow: Ensure the system's minimum volumetric flow can keep the disc in open position (refer to pressure drop chart "Full open/stable range").
4. Pulsating flow conditions: If the system has pulsating flow (e.g., downstream of compressors), specially designed check valves should be selected. It is recommended to consult the manufacturer for pressure drop calculation and selection.
5. Static electricity protection: After installation, the equipment and connected system may generate static electricity. If used in explosive environments, the equipment manufacturer or owner is responsible for static electricity protection or grounding.
6. Media leakage considerations: If there is a risk of media leakage (e.g., through actuators or threaded connections), the equipment manufacturer or owner must consider this during area classification.

Chemical Compatibility

For information on chemical compatibility between valve materials and specific media, visit www.gestra.com, navigate to "Technical Support" and "Chemical resistance" for detailed information.

Quotation and Ordering Requirements

When ordering, the following parameters must be specified:

• Media type
• Flow requirements
• Working pressure and temperature
• Pipeline flange standard
• Seat material selection (metal-to-metal/EPDM/FPM/PTFE)
• Cracking pressure requirements (standard or special spring)
• Special treatment requirements (e.g., silicone-free, oil-free and grease-free, pickling and passivation)

Acceptance Testing

EN 10204 standard inspection certificates can be provided as verification evidence for material and construction testing. All testing requirements must be clearly stated in the quotation request or order. Inspection certificates will not be issued after delivery. Standard testing scope and costs are detailed in the price list "Standard Equipment Testing and Inspection Costs". For customized testing scope, please request a separate quotation.

EU Directive Compliance

• Pressure Equipment Directive (PED): The product complies with this directive and is suitable for Group 1 and Group 2 media.
• ATEX Directive: The product has no inherent potential ignition source and is not subject to this directive.