Krishna Industries (KELOR), based in Ahmedabad, Gujarat, is a B2B supplier of CF8 / CF8M Dual Plate Check Valves — ASTM A351 CF8 (SS304) and CF8M (SS316) cast stainless steel body — SS316 half-discs — SS316 hinge pin and torsion springs — EPDM, NBR, PTFE, and metal-to-metal seat — wafer and lug type — DN50 to DN600 — PN10, PN16, Class 150, Class 300 — API 594 / BS 5153 / EN 12334 — API 598 tested — GST invoice — MOQ 10 Nos — Pan India dispatch from Ahmedabad.
The CF8 / CF8M dual plate check valve is the stainless steel body specification for dual plate non-return valve service in chemical plants, pharmaceutical facilities, marine and coastal installations, food and beverage plants, and any application where a CI (cast iron) or WCB (carbon steel) body dual plate check valve would corrode in the service environment or be rejected by the project piping specification. CF8 (SS304 equivalent) for general corrosive and chemical service. CF8M (SS316 equivalent) where chlorides, aggressive acids, or higher corrosion resistance is required.
CF8 vs CF8M — Key Differences and When to Specify Each
Feature
CF8 (SS304 Equivalent)
CF8M (SS316 Equivalent)
ASTM Grade
ASTM A351 CF8
ASTM A351 CF8M
Wrought Equivalent
SS304 (UNS S30400)
SS316 (UNS S31600)
Composition
18% Chromium, 8% Nickel — no molybdenum
16% Chromium, 10% Nickel, 2% Molybdenum
Chloride Resistance
Moderate — pitting risk in chloride-rich water above ~200 ppm Cl⁻
✅ Better — molybdenum passivates against chloride pitting
Acid Resistance
Good for dilute acid, acetic acid, food acids
✅ Better for mineral acids — HCl, H2SO4, H3PO4
Marine / Coastal
Limited — seawater pitting risk
✅ Standard — used in marine and coastal chemical service
Pharmaceutical
Acceptable for WFI and PW where chloride levels are low
✅ Preferred — GMP standard for pharma API and process water
Food and Beverage
✅ Acceptable for most food contact — FDA compliant
✅ Preferred where CIP uses chlorinated cleaners
Cost
✅ Lower — no molybdenum premium
Higher — Mo content adds 15–25% over CF8
Specify When
✅ General corrosive media, food, pharma water, dilute chemical, non-chloride service, coastal fresh water
✅ Chloride-rich water, seawater, mineral acids, aggressive chemical, pharma API, marine, CIP with chlorinated cleaners
Dual Plate vs Single Plate Check Valve — Why Dual Plate for Large Bore
Feature
Dual Plate (Double Door)
Single Plate (Single Disc)
Disc Design
Two semi-circular half-discs on central hinge pin — each disc = half bore area
One full disc on hinge pin
Disc Mass per Spring
✅ Low — each half-disc is light — soft torsion spring sufficient
High at large bore — heavier disc needs stiffer spring
Cracking Pressure
✅ Very low — soft springs, light discs — opens at low flow velocity
Higher at large bore — stiff spring = higher cracking pressure
Pressure Drop
✅ Lower — two half-discs fold back more compactly against hinge pin
Higher at large bore — full disc partially obstructs flow even when open
Water Hammer
✅ Very low — two light discs close faster than one heavy disc
Low — spring assisted, better than swing check
Best Size Range
✅ DN50 to DN600 — standard for DN200 and above
DN15 to DN200 — preferred at small bore for lower cost
Cost at Large Bore
✅ More economical than single plate at DN200+
Higher at DN200+ due to heavy disc and stiff spring
Specify When
✅ DN200 and above — all sizes where low cracking pressure and low pressure drop are critical — standard for pump headers, main process lines
DN15–DN150 — pump discharge utility service at smaller bore
Seat and Seal Material Guide
Seat Material
Temperature
Media Compatibility
Specify For
EPDM
-30°C to +150°C
Water, dilute acid/alkali, steam, ozone — NOT oil/fuel/solvents
✅ Standard for water, HVAC, pharma water, general chemical — most common with CF8 body
NBR (Buna-N)
-20°C to +80°C
Oil, fuel, hydraulic fluid, petroleum — NOT acids, ozone
Oil and fuel service — offshore utility, fuel transfer
PTFE
-40°C to +180°C
✅ Broad chemical resistance — FDA compliant
✅ Standard with CF8M for chemical plant, pharma API, aggressive acid/alkali, food CIP
Metal-to-Metal (SS316)
Up to 400°C
Steam, thermic fluid, high temp — no elastomer
High temperature steam, thermic fluid, boiler feed — where elastomer seats cannot be used
Technical Specifications
Parameter
CF8 (SS304)
CF8M (SS316)
Body Material Standard
ASTM A351 CF8
ASTM A351 CF8M
Disc Material
SS316 (standard) — half-disc, spring loaded
Hinge Pin
SS316
Spring
SS316 torsion spring (standard) / Inconel (high temp on request)
Seat / Body Seal
EPDM (standard)
PTFE (standard) / EPDM / NBR / metal
Design Standard
API 594 / BS 5153 / EN 12334
Testing Standard
API 598 / EN 12266
Face-to-Face
API 594 short pattern / ASME B16.10
Body Style
Wafer (standard) / Lug type
Size Range
DN50 to DN600 (2″ to 24″) — DN50–DN300 stock; DN350–DN600 sourced to order
Pressure Rating
PN10 / PN16 / Class 150
PN10 / PN16 / Class 150 / Class 300
Temperature Range
-10°C to +150°C (EPDM seat)
-10°C to +180°C (PTFE seat)
Flow Direction
Unidirectional — arrow marked on body
Installation
Horizontal and vertical (upward flow)
MOQ
10 Nos
HSN Code
84814000
Applications in Indian Industries
Chemical plants — Gujarat belt (Ankleshwar, Vapi, Dahej, Bharuch) — CF8M PTFE — large bore pump discharge headers DN100–DN300, process line NRV where CI body corrodes in chemical atmosphere and splash, piping class requiring CS or SS body
Pharmaceutical plants — CF8M EPDM or PTFE — purified water (PW) and WFI distribution pump discharge, CIP return headers, API process water NRV — GMP compliant, smooth internal surfaces
Marine and offshore — CF8M PTFE or NBR — seawater cooling systems, offshore platform utility water, marine bilge and ballast — molybdenum essential for seawater chloride resistance
Coastal industrial plants — CF8M EPDM — coastal city water supply and HVAC systems where chloride content in water supply is elevated — Mumbai, Chennai, Vizag, Kochi coastal industrial zones
Food and beverage processing — CF8 or CF8M PTFE — process water pump discharge, CIP distribution headers, juice and dairy product lines — FDA compliant PTFE seat, smooth bore
Power plant auxiliary — CF8M metal seat — demineralised water, cooling water chemical dosing headers, condensate polishing — stainless body required for DM water service (CI corrodes in DM water)
Fertiliser and petrochemical — CF8M PTFE Class 150 — process chemical utilities, wash water systems, effluent headers — where piping class requires SS body
ETP/STP chemical dosing headers — CF8 EPDM — ferric chloride, NaOH, HCl dosing pump discharge — stainless body resists chemical splash and vapour corrosion in chemical dosing areas
Related Products — Krishna Industries (KELOR)
Dual Plate Check Valve — CI / WCB Body — for general water supply, HVAC, fire fighting, and utility service where stainless body not required — more economical for non-corrosive service
SS304 Wafer Check Valve — single plate NRV in CF8 body for smaller bore DN40–DN150 where dual plate is over-specified
SS316 Wafer Check Valve — CF8M single plate NRV for aggressive chemical and pharma service at smaller bore
Spring Loaded Silent Check Valve — nozzle/poppet type for high-velocity pump discharge and boiler feed water where dual plate disc chatter is a concern
Y Strainer Valve — install upstream to protect dual plate disc hinge pin and seat from pipeline debris
Frequently Asked Questions
1. What is the difference between CF8 and CF8M?
CF8 is the cast equivalent of SS304 — 18% chromium, 8% nickel, no molybdenum. CF8M is the cast equivalent of SS316 — 16% chromium, 10% nickel, plus 2% molybdenum. The molybdenum in CF8M significantly improves resistance to chloride pitting corrosion and general acid attack. For seawater, marine, coastal, and chloride-rich service, CF8M is mandatory. For general fresh water, food, and pharmaceutical service, CF8 is acceptable and more economical. When in doubt on a chemical plant application, specify CF8M.
2. Why dual plate instead of single plate for large bore?
At DN200 and above, a single plate full disc becomes very heavy — the spring required to close it quickly enough to prevent water hammer must be very stiff, which raises cracking pressure and makes the valve difficult to open at low flow velocity. A dual plate valve splits the bore into two half-discs, each of which is light and needs only a soft torsion spring. This gives lower cracking pressure, lower pressure drop, and faster, quieter closure at large bore. Dual plate is the standard specification for DN200 and above in all body materials.
3. What seat to specify for chemical plant service with CF8M body?
PTFE seat is standard with CF8M body for chemical plant service — it provides broad chemical resistance across most acid, alkali, solvent, and oxidising media, is FDA compliant for food contact, and handles temperatures up to 180°C. EPDM is used with CF8M for pharma water and general non-chemical service. Metal-to-metal seat is specified for steam and high temperature service above 180°C where PTFE would soften.
4. Is CF8M suitable for seawater service?
CF8M provides good resistance to seawater in moderate temperature and flow conditions — the molybdenum addition passivates against chloride pitting that would rapidly attack CF8. For higher temperature seawater above 60°C or stagnant seawater conditions, duplex stainless (e.g. A890 CD3MN) is preferred over CF8M. For Indian coastal and marine utility applications at ambient temperature, CF8M PTFE is the standard and accepted specification.
5. What is the difference between wafer and lug type?
Wafer type is sandwiched between pipe flanges with through-bolts — both pipe ends must remain flanged. Lug type has threaded inserts in the body — bolts from each side thread into the valve independently, allowing one pipe side to be removed without disturbing the other. Specify lug type for end-of-line installation or where single-side pipe removal is required during maintenance. Wafer type for standard in-line service.
6. What is the MOQ?
MOQ is 10 Nos. Project orders for chemical plant, pharma, marine, or process piping — 20 to 200+ Nos across sizes — with hydro test reports, MTR (ASTM A351 CF8/CF8M), and API 598 test certificates. Specify CF8 or CF8M, seat material, wafer or lug, pressure class, and size list for project pricing.
Conclusion
The CF8 / CF8M Dual Plate Check Valve supplied by Krishna Industries (KELOR) is the stainless steel non-return valve for Indian chemical plants, pharmaceutical facilities, marine, coastal, food and beverage, and corrosive media service — ASTM A351 CF8 (SS304) and CF8M (SS316) body — SS316 half-discs and hinge pin — EPDM, NBR, PTFE, metal-to-metal seat — wafer and lug type — DN50 to DN600 — PN10, PN16, Class 150, Class 300 — API 594 / EN 12334 — API 598 tested — MTR on request. GST invoice, Pan India dispatch from Ahmedabad. WhatsApp body grade (CF8 or CF8M), seat material, pressure class, body style, size list, and quantity for bulk pricing within 2 hours.
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