Duplex Strainer Supplier India | SS316 WCB CI | Manual Auto Changeover | Class 150 | DN25–DN300 | Continuous Filtration

Description

Duplex Strainer Supplier India | SS316 / WCB / CI | Manual & Automatic Changeover | Class 150 / Class 300 | DN25–DN300 | Continuous Filtration | KELOR

Supplier: Krishna Industries (KELOR) – Ahmedabad, Gujarat, India
Established: 2017 | GSTIN: 24AKLPP6499B1ZT | IEC: AKLPP6499B
MOQ: 10 Nos | Body: SS316 (primary) / WCB / CI
Changeover: Manual lever / Automatic pneumatic | Sizes: DN25–DN300

Duplex Strainer Supplier in India — Continuous Filtration, No Shutdown to Clean

Krishna Industries (KELOR), based in Ahmedabad, Gujarat, is a B2B supplier of Duplex Strainers — SS316 (CF8M), WCB, and Cast Iron body — SS316 perforated basket with mesh lining — manual lever or automatic pneumatic changeover valve — integral differential pressure (ΔP) gauge — bolted cover — flanged ASME B16.5 — DN25 to DN300 — Class 150 / Class 300 — custom mesh from 20 micron to 3mm — MTC and hydro test report on request — GST invoice — MOQ 10 Nos — Pan India dispatch from Ahmedabad.

A duplex strainer provides continuous pipeline filtration without any process shutdown for basket cleaning. While one basket chamber is in service filtering the process fluid, the other chamber is isolated, depressurised, and available for cleaning — cover removed, basket cleaned, cover replaced, chamber re-pressurised — then the changeover valve switches flow to the clean chamber. The process line never stops flowing. This is the reason duplex strainers are specified for continuous process plants, critical pump protection, and any service where shutting down a single Y strainer or basket strainer to clean it is not acceptable.

How the Duplex Strainer Works — Changeover Sequence

Understanding the changeover sequence is essential for correct installation and operation. The duplex strainer has two identical basket chambers — Chamber A and Chamber B — connected to a common inlet header and outlet header through the central changeover valve body.

Normal operation — Chamber A in service: Changeover valve directs all flow through Chamber A basket. Chamber B is isolated — both inlet and outlet ports to B are closed. Chamber B is at zero pressure — cover can be safely removed at any time.

Switching to Chamber B: Operator turns manual lever (or pneumatic actuator operates automatically) to intermediate position — briefly both chambers are in parallel — flow continues uninterrupted, pressure drop actually decreases momentarily. Lever continues to full B position — Chamber A is now isolated, Chamber B is in full service.

Cleaning Chamber A: Chamber A is at zero pressure. Remove bolted cover. Lift out basket. Clean basket with compressed air, water jet, or by dipping in cleaning solution. Inspect mesh for damage. Replace basket. Refit cover. Tighten cover bolts evenly. Chamber A is now ready for next switchover.

Key point: at no point during this sequence does the process line stop flowing. The pump continues running, the process continues, and the system pressure is maintained throughout.

Manual Changeover vs Automatic Changeover

Duplex Strainer vs Y Strainer — When to Specify Which

Mesh Size Selection Guide

Technical Specifications

Applications in Indian Industries

• Pharmaceutical plants — Hyderabad, Baddi, Ahmedabad — SS316 manual changeover — 50–150 micron mesh — purified water (PW) distribution loop filtration, WFI loop protection, API process line filtration — continuous operation mandatory for GMP batch compliance — shutdown for Y strainer cleaning causes batch interruption
• Chemical plants — Ankleshwar, Vapi, Dahej — SS316 manual or automatic changeover — 250–500 micron mesh — corrosive chemical pump protection, reactor feed filtration, solvent transfer pump suction protection — SS316 body resists chemical attack — continuous operation essential in exothermic reactor feed lines
• Power plant BFW and condensate — WCB automatic changeover — 150–250 micron mesh — boiler feed pump suction protection, condensate extraction pump protection — automatic ΔP switchover protects BFP from ingestion of scale or condenser tube debris — DCS integrated alarm
• Refinery pump protection — WCB manual changeover — 500 micron mesh — crude charge pump suction, reflux pump suction, product pump suction — high particle loading in crude service — large basket holds more debris between cleanings than Y strainer
• Food and beverage — dairy, beverage, brewery — SS316 manual changeover — 50–150 micron mesh — PTFE gaskets — product line filtration — continuous production line cannot be stopped to clean strainer — GMP food contact compliance
• Offshore oil and gas — Duplex or SS316 body — automatic changeover — seawater lift pump protection, produced water injection pump protection — unmanned platform requires automatic ΔP switchover — NAMUR proximity sensor on changeover valve for SIL-rated systems

Related Products — Krishna Industries (KELOR)

• Y Strainer — for non-continuous service where pipeline can be shut down briefly for screen cleaning — more compact and economical than duplex strainer for moderate particle loading
• SS Butterfly Valve — CF8/CF8M — for isolation upstream and downstream of duplex strainer in pharma, chemical, and food lines
• Pneumatic Ball Valve — automated isolation valve to pair with automatic changeover duplex strainer in DCS-controlled systems
• CF8 CF8M Dual Plate Check Valve — for pump discharge NRV in chemical and pharma pump stations where SS body is required throughout
• Flanged Ball Valve — for manual isolation of strainer chambers during maintenance in WCB or CF8M Class 150

Frequently Asked Questions

1. Can the process line really keep running while cleaning a duplex strainer basket?

Yes — this is the fundamental design purpose of a duplex strainer. When the operator moves the changeover lever to switch from Chamber A to Chamber B, there is a brief moment when both chambers are in parallel service — the process line never stops flowing and pressure is maintained throughout. Once Chamber A is isolated, it is at zero pressure and can be opened safely for basket cleaning. The pump keeps running, the process continues, and the system sees no interruption. This is why duplex strainers are specified in continuous process plants, pharmaceutical manufacturing, and food production lines where stopping the process has significant cost or compliance consequences.

2. What mesh size should I specify for pump protection?

For centrifugal pump protection — general process service — 500 micron (0.5mm) mesh lining on 3mm perforated plate is the standard Indian process plant specification. This stops particles that would damage wearing rings and mechanical seals while maintaining acceptable pressure drop. For boiler feed pumps (BFP) — 250 micron — finer protection for the close-clearance BFP impeller wearing rings and balance disc. For control valve protection upstream of cage trim control valves — 150 micron. Always specify both the perforated plate hole size AND the mesh micron rating — “3mm perf with 500 micron mesh” — to avoid ambiguity in supply.

3. How do I know when to switch chambers?

Each chamber has a differential pressure (ΔP) gauge showing pressure drop across the active basket. A clean basket at design flow typically shows 0.1–0.3 bar ΔP. As the basket collects debris, ΔP rises. The maximum allowable ΔP before switching is set by the project specification — typically 0.5–1.0 bar for most Indian process plant applications. Operator makes rounds and reads the ΔP gauge — when it approaches the maximum, the chamber is switched. For automatic changeover units, a ΔP switch is set to the maximum allowable value and triggers the pneumatic actuator automatically.

4. What is the difference between a duplex strainer and a basket strainer?

A basket strainer is a single-chamber strainer with a large cylindrical basket — larger screen area and lower pressure drop than a Y strainer — but it is still a single strainer requiring shutdown to clean. A duplex strainer is two basket strainers in one body with a changeover valve — it has all the basket strainer advantages (large screen area, low ΔP) plus continuous operation capability. For non-critical service where the line can be shut down occasionally, a basket strainer is economical. For continuous process service, duplex is required.

5. What is the MOQ and what documentation is available?

MOQ is 10 Nos. Pharma, chemical, or power plant project orders — 5 to 50+ Nos across sizes — with material test certificates (ASTM A351 CF8M for SS316 body, ASTM A216 WCB), hydrostatic pressure test report, dimensional inspection report, and GST invoice. For automatic changeover units — ΔP switch datasheet, actuator torque data, and wiring diagram supplied. WhatsApp body material, size, Class, mesh specification, changeover type, and quantity for project pricing within 2 hours.

Conclusion

The Duplex Strainer supplied by Krishna Industries (KELOR) is the continuous-operation pipeline filtration solution for Indian process plants — SS316 (CF8M), WCB, and Cast Iron body — SS316 perforated basket with mesh lining (20 micron to 3mm) — manual lever or automatic pneumatic changeover valve — integral ΔP gauge on each chamber — bolted cover — flanged ASME B16.5 — DN25 to DN300 — Class 150 / Class 300. Pharmaceutical, chemical, food processing, power plant BFW/condensate, refinery, offshore — wherever the pipeline cannot be shut down to clean a single strainer. MTC, hydro test report, ΔP switch datasheet on request. GST invoice, Pan India dispatch from Ahmedabad. WhatsApp body material, size, Class, mesh specification, changeover type, and quantity for project pricing within 2 hours.