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Knappe Pressure Vessels

Knappe Composites manufactures compact FRP membrane housings, RO pressure vessels, Xtype skids, and stainless components for RO and NF systems.Its The brand emphasizes more than 40 years of expertise, in-house manufacturing, and EU PED / ASME Section X design, making it relevant where vessel compactness and code expectations shape skid design.

Knappe Pressure Vessels's position in RO/NF membranes and related equipment is defined by product families such as 4" Front Port Pressure Vessels, 8" Side Port Pressure Vessels, 8" Front Port Pressure Vessels and Extra information.

The portfolio is best understood inside brackish water, seawater desalination, ultrapure water, process separation, reuse, degassing, and membrane system packaging, where engineers compare the technology route, family boundaries, and duty fit before narrowing to individual models.Representative series on this page include Serie 4" V4i 21, Permeat assembly and Feed assembly.Engineers should compare element size, salt rejection, permeate flow, pressure rating, fouling resistance, connection type, and vessel fit.

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Indexed models

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Model index

Dong san pham va huong dan lua chon

Cach chon Pressure Vessels cua Knappe

Phan nay tra loi hai cau hoi: Knappe co nhung dong san pham chinh nao, va can so sanh nhung thong so nao truoc khi chon model cu the.

Buoc 1: Chon dong san pham theo ung dung

Cac dong san pham chinh tren trang nay gom 4" Front Port Pressure Vessels, 8" Side Port Pressure Vessels, 8" Front Port Pressure Vessels, and Extra information. Hay chon dong phu hop voi muc tieu xu ly, dang thiet bi va dieu kien van hanh truoc, sau do dung chi muc model ben duoi de so sanh thong so cu the.

Buoc 2: Xac nhan model bang thong so chinh

Sau khi chon dong san pham, hay so sanh pressure rating, element count, port layout, and code requirement. Du an thay the cung phai kiem tra dieu kien lap dat, giao dien va kha nang tuong thich voi he thong hien huu; du an moi can xem them cach van hanh, bao tri va nguon phu tung hoac vat tu.

Product family overview

4 product familys on this page.

4" Front Port Pressure Vessels

8 models in this family. Representative models: Serie 4" V4i 21, Permeat assembly, Feed assembly.

8" Side Port Pressure Vessels

9 models in this family. Representative models: Serie 8" 3Ss 21, Permeat assembly, Feed assembly.

8" Front Port Pressure Vessels

11 models in this family. Representative models: Serie 8"V2s 21, Permeat assembly, Feed assembly.

Extra information

6 models in this family. Representative models: Knappe Catalog 8" Pressure Vessels, Knappe AnyParts, Knappe AnyRack Single.

Quick Model Index

Fast lookup for 34 indexed products

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Products & documents

Showing 34 of 34 models

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Serie 4" V4i 21

4" Front Port Pressure Vessels

Max. Working Pressure: 21 bar (300 PSI) · Max Test Pressure (ASMEX): 27.3 bar (390 PSI) · Max. Working Temperature: 65 °C (150 °F)

This is a 4-inch front-entry reverse osmosis membrane pressure vessel from Knappe's V4i series.

DetailsPDF

Permeat assembly

4" Front Port Pressure Vessels

Pressure: 300 PSI · Manufacturer/Material: Knappe Composites Mat.: 14EP4

This is a Knappe endplate assembly for 4-inch RO membrane vessels, designed for the permeate/brine side application. It supports various union options rated up to 300 PSI.

DetailsPDF

Feed assembly

4" Front Port Pressure Vessels

Pressure rating: 300 PSI possible

This is a Knappe Pressure Vessels feed assembly, model 14EP4-C, designed as an endplate for RO membrane housings.

DetailsPDF

Serie 4" V4i 31

4" Front Port Pressure Vessels

Permeate optional port: G3/4in cylindrical (different styles available) · Max. Working Pressure: 31 bar (450 PSI) · Max. Test Pressure (ASMEX): 40.3 bar (585 PSI)

The Knappe Pressure Vessels Serie 4" V4i 31 is a front-entry reverse osmosis membrane pressure vessel.

DetailsPDF

Serie 4" V4i 42

4" Front Port Pressure Vessels

HEAD ENDPLATE open: 74EP4, PPE · Max. Working Pressure: 42 bar / 600 PSI · Max. Test Pressure (ASMEX): 54.6 bar / 780 PSI

The Knappe Pressure Vessels Serie 4" V4i 42 is a front-entry reverse osmosis membrane housing designed for one to six elements.

DetailsPDF

Serie 4" V3 70

4" Front Port Pressure Vessels

Max. Working Pressure: 70 bar / 1000 PSI · Max. Test Pressure (ASMEX): 91 bar / 1300 PSI · PermeatePort Adapter: PVC

This is a Knappe Composites 4-inch front-entry RO membrane pressure vessel designed for reverse osmosis systems.

DetailsPDF

Permeat assembly

4" Front Port Pressure Vessels

Location A (Permeate): 16x3 (Qty: 1) · Material ID: 14STOSW3/P · Location C (HP-Port): 22x3 (Qty: 1)

This is a Permeat assembly from Knappe Pressure Vessels, designed for use with RO membrane systems.

DetailsPDF

Feed assembly

4" Front Port Pressure Vessels

Selection cues: housing diameter · pressure rating · port format and element count

This is a Knappe feed assembly designed for RO membrane pressure vessels.

DetailsPDF

Serie 8" 3Ss 21

8" Side Port Pressure Vessels

Permeate Port Body: 78PP/BSP (PPE) · Max. Working Pressure: 21 bar / 300 PSI · Max. Test Pressure acc. ASME X: 27.3 bar / 390 PSI

The Knappe Serie 8" 3Ss 21 is an 8-inch diameter, multi-element brackish water reverse osmosis pressure vessel.

DetailsPDF

Permeat assembly

8" Side Port Pressure Vessels

Selection cues: housing diameter · pressure rating · port format and element count

This is an Endplate ASSY Sideport for the Knappe Series S3s RO membrane pressure vessels.

DetailsPDF

Feed assembly

8" Side Port Pressure Vessels

Selection cues: housing diameter · pressure rating · port format and element count

Feed assembly is a membrane housing or pressure vessel for RO/NF membrane systems, best compared by port format, element count, and installation envelope.

DetailsPDF

Serie 8" 3Ss 31

8" Side Port Pressure Vessels

Max. Working Pressure: 31 bar (450 PSI) · Max. Test Pressure (acc. ASME X): 40.3 bar (585 PSI) · Permeate Port Body (Part # 78PP/BSP): PPE

The Knappe Series 8" 3Ss 31 are 8-inch diameter sideport brackishwater reverse osmosis membrane pressure vessels designed for 60-inch elements.

DetailsPDF

Serie 8" 3p 42

8" Side Port Pressure Vessels

Max. Working Pressure: 42 bar / 600 PSI · Max Test Pressure (acc. ASME X): 54.3 bar / 780 PSI · Permeate Port Body: PPE

The Knappe Pressure Vessels Serie 8" 3p 42 is an 8-inch diameter brackish water RO membrane pressure vessel rated for 600 PSI. It features a FRP shell, PVC liner.

DetailsPDF

Permeat assembly

8" Side Port Pressure Vessels

Selection cues: housing diameter · pressure rating · port format and element count

This is an Endplate Assembly for Knappe Pressure Vessels' Series S3p, designed for RO membrane applications.

DetailsPDF

Feed assembly

8" Side Port Pressure Vessels

Selection cues: housing diameter · pressure rating · port format and element count

This is an endplate assembly designed as a sideport for Knappe Pressure Vessels Series S3p, with a closed permeate.

DetailsPDF

Serie 8" SXp 70

8" Side Port Pressure Vessels

Max. Working Pressure: 70 bar / 1000 PSI · Max. Test Pressure (ASMEX): 91 bar / 1300 PSI · Permeate Port Body: PPE

The Knappe Pressure Vessels Serie 8" SXp 70 is an 8-inch diameter FRP and PVC reverse osmosis membrane pressure vessel designed for seawater applications.

DetailsPDF

Feed assembly

8" Side Port Pressure Vessels

Selection cues: housing diameter · pressure rating · port format and element count

This is an Endplate Assembly Sideport for Knappe Composites Series S3p, designed with a permeate closed configuration.

DetailsPDF

Serie 8"V2s 21

8" Front Port Pressure Vessels

Max. Working Pressure: 21 bar (300 PSI) · Max. Test Pressure: 27.3 bar (390 PSI) · Permeate Port Body open: PPE

This is a Knappe Pressure Vessels Series 8"V2s 21 front-entry membrane housing designed for brackish water applications.

DetailsPDF

Permeat assembly

8" Front Port Pressure Vessels

Selection cues: housing diameter · pressure rating · port format and element count

This is a front port endplate assembly designed for RO membrane pressure vessels by Knappe Composites.

DetailsPDF

Feed assembly

8" Front Port Pressure Vessels

Selection cues: housing diameter · pressure rating · port format and element count

This is a feed assembly for RO membrane pressure vessels, including various EPDM O-rings. It is an O-rings and endplate assembly with additional listed components.

DetailsPDF

Serie 8"V2s 31

8" Front Port Pressure Vessels

Max. Working Pressure: 31 bar / 450 PSI · Max. Test Pressure: 40.3 bar / 585 PSI

The Knappe Pressure Vessels Serie 8"V2s 31 is an 8-inch front-entry FRP pressure vessel designed for brackish water applications and can house multiple 40-inch membrane...

DetailsPDF

Serie 8"V2s 42

8" Front Port Pressure Vessels

Max. Working Pressure: 42 bar (600 PSI) · Max. Test Pressure: 54.6 bar (780 PSI) · Permeate Port Body: PPE

The Knappe Pressure Vessels Serie 8"V2s 42 is an 8-inch front-entry reverse osmosis membrane pressure vessel. It is constructed with an FRP shell, PVC liner.

DetailsPDF

Permeat assembly

8" Front Port Pressure Vessels

Selection cues: housing diameter · pressure rating · port format and element count

This permeate assembly is the Endplate ASSY Frontport model 18EP-M-BW-V2s from Knappe Pressure Vessels, designed for RO membrane systems.

DetailsPDF

Feed assembly

8" Front Port Pressure Vessels

Material Code: 18EP-M-BW-V2s/C

This feed assembly is designed for RO membrane pressure vessels. It includes multiple EPDM O-rings for sealing.

DetailsPDF

Serie 8"V2 70

8" Front Port Pressure Vessels

Max. Working Pressure: 69 bar (1000 PSI) · Max. Test Pressure: 89.7 bar (1300 PSI) · Permeate Port Body: PVC

This is a Knappe Series 8" V2 70 front-entry RO membrane pressure vessel designed for reverse osmosis applications.

DetailsPDF

Permeat assembly

8" Front Port Pressure Vessels

Pressure Rating: 1000/1200 PSI · Pressure: 1200 PSI

This is a Knappe Permeat assembly, the front endplate for RO membrane pressure vessels. It is rated for 1000/1200 PSI and includes EPDM O-rings for sealing.

DetailsPDF

Feed assembly

8" Front Port Pressure Vessels

Pressure rating: 1000/1200 PSI · Pressure: 1200 PSI

This Knappe Pressure Vessels feed assembly is designed for RO membrane systems. It features EPDM O-rings and is rated for pressures up to 1200 PSI.

DetailsPDF

Serie 8"V2 84

8" Front Port Pressure Vessels

Max. Working Pressure: 84 bar (1200 PSI) · Max. Test Pressure: 109 bar (1560 PSI) · Permeate Port Body: PPE

The Knappe Serie 8"V2 84 is an 8-inch, front-entry FRP seawater RO membrane pressure vessel.

DetailsPDF

Knappe Catalog 8" Pressure Vessels

Extra information

Selection cues: housing diameter · pressure rating · port format and element count

Knappe Catalog 8" Pressure Vessels are designed as RO membrane housings featuring the AnyClic self-sealing endplate and AnyDistance shimming system.

DetailsPDF

Knappe AnyParts

Extra information

Selection cues: housing diameter · pressure rating · port format and element count

These Knappe AnyParts are permeate port adapters designed for RO membrane housings. Available in various materials like PVC, PA66, PP, and SS 316L.

DetailsPDF

Knappe AnyRack Single

Extra information

Selection cues: housing diameter · pressure rating · port format and element count

The Knappe AnyRack Single is an RO membrane pressure vessel designed for water treatment applications.

DetailsPDF

Knappe AnyRack Double

Extra information

Selection cues: housing diameter · pressure rating · port format and element count

The Knappe AnyRack Double is a pressure vessel designed for RO membrane systems.

DetailsPDF

Knappe Assembly & Operating Instructions 4 inch

Extra information

Compatibility: Suitable for male membranes with a centercore tube OD19.2mm

This is a 4-inch front port composite vessel designed for RO/UF applications, built to ASME X code for brackish or seawater desalination. It features food-grade PVC, PPE.

DetailsPDF

Knappe Assembly & Operating Instructions 8 inch

Extra information

Permeate stream pressure limit: Should not exceed 150 PSI / 10 bars (unless certified differently) · Permeate port: Not to exceed 4 kg · Over-pressure protection: Essential that pressure to which any vessel is subjected cannot exceed 105% of design pressure

This composite vessel is designed for reverse osmosis, nanofiltration, and ultrafiltration applications, housing any make of 8-inch spiral-wound membrane elements.

DetailsPDF

Brand Products & Technical Documents

34 product profiles with integrated document access

Each card keeps the curated model introduction and combines the readable datasheet page, OEM PDF, and official source. Product understanding and document access now share one card set.

4" Front Port Pressure Vessels

8 product profiles

Pressure Vessels
Knappe logo

Product profile

Serie 4" V4i 21

This is a 4-inch front-entry reverse osmosis membrane pressure vessel from Knappe's V4i series.

Pressure Vessels
Knappe logo

Product profile

Permeat assembly

This is a Knappe endplate assembly for 4-inch RO membrane vessels, designed for the permeate/brine side application. It supports various union options rated up to 300 PSI.

Pressure Vessels
Knappe logo

Product profile

Feed assembly

This is a Knappe Pressure Vessels feed assembly, model 14EP4-C, designed as an endplate for RO membrane housings.

Pressure Vessels
Knappe logo

Product profile

Serie 4" V4i 31

The Knappe Pressure Vessels Serie 4" V4i 31 is a front-entry reverse osmosis membrane pressure vessel.

Pressure Vessels
Knappe logo

Product profile

Serie 4" V4i 42

The Knappe Pressure Vessels Serie 4" V4i 42 is a front-entry reverse osmosis membrane housing designed for one to six elements.

Pressure Vessels
Knappe logo

Product profile

Serie 4" V3 70

This is a Knappe Composites 4-inch front-entry RO membrane pressure vessel designed for reverse osmosis systems.

Show remaining 4" Front Port Pressure Vessels profiles (2)
Pressure Vessels
Knappe logo

Product profile

Permeat assembly

This is a Permeat assembly from Knappe Pressure Vessels, designed for use with RO membrane systems.

Pressure Vessels
Knappe logo

Product profile

Feed assembly

This is a Knappe feed assembly designed for RO membrane pressure vessels.

8" Side Port Pressure Vessels

9 product profiles

Pressure Vessels
Knappe logo

Product profile

Serie 8" 3Ss 21

The Knappe Serie 8" 3Ss 21 is an 8-inch diameter, multi-element brackish water reverse osmosis pressure vessel.

Pressure Vessels
Knappe logo

Product profile

Permeat assembly

This is an Endplate ASSY Sideport for the Knappe Series S3s RO membrane pressure vessels.

Pressure Vessels
Knappe logo

Product profile

Feed assembly

Feed assembly is a membrane housing or pressure vessel for RO/NF membrane systems, best compared by port format, element count, and installation envelope.

Pressure Vessels
Knappe logo

Product profile

Serie 8" 3Ss 31

The Knappe Series 8" 3Ss 31 are 8-inch diameter sideport brackishwater reverse osmosis membrane pressure vessels designed for 60-inch elements.

Pressure Vessels
Knappe logo

Product profile

Serie 8" 3p 42

The Knappe Pressure Vessels Serie 8" 3p 42 is an 8-inch diameter brackish water RO membrane pressure vessel rated for 600 PSI. It features a FRP shell, PVC liner.

Pressure Vessels
Knappe logo

Product profile

Permeat assembly

This is an Endplate Assembly for Knappe Pressure Vessels' Series S3p, designed for RO membrane applications.

Show remaining 8" Side Port Pressure Vessels profiles (3)
Pressure Vessels
Knappe logo

Product profile

Feed assembly

This is an endplate assembly designed as a sideport for Knappe Pressure Vessels Series S3p, with a closed permeate.

Pressure Vessels
Knappe logo

Product profile

Serie 8" SXp 70

The Knappe Pressure Vessels Serie 8" SXp 70 is an 8-inch diameter FRP and PVC reverse osmosis membrane pressure vessel designed for seawater applications.

Pressure Vessels
Knappe logo

Product profile

Feed assembly

This is an Endplate Assembly Sideport for Knappe Composites Series S3p, designed with a permeate closed configuration.

8" Front Port Pressure Vessels

11 product profiles

Pressure Vessels
Knappe logo

Product profile

Serie 8"V2s 21

This is a Knappe Pressure Vessels Series 8"V2s 21 front-entry membrane housing designed for brackish water applications.

Pressure Vessels
Knappe logo

Product profile

Permeat assembly

This is a front port endplate assembly designed for RO membrane pressure vessels by Knappe Composites.

Pressure Vessels
Knappe logo

Product profile

Feed assembly

This is a feed assembly for RO membrane pressure vessels, including various EPDM O-rings. It is an O-rings and endplate assembly with additional listed components.

Pressure Vessels
Knappe logo

Product profile

Serie 8"V2s 31

The Knappe Pressure Vessels Serie 8"V2s 31 is an 8-inch front-entry FRP pressure vessel designed for brackish water applications and can house multiple 40-inch membrane...

Pressure Vessels
Knappe logo

Product profile

Serie 8"V2s 42

The Knappe Pressure Vessels Serie 8"V2s 42 is an 8-inch front-entry reverse osmosis membrane pressure vessel. It is constructed with an FRP shell, PVC liner.

Pressure Vessels
Knappe logo

Product profile

Permeat assembly

This permeate assembly is the Endplate ASSY Frontport model 18EP-M-BW-V2s from Knappe Pressure Vessels, designed for RO membrane systems.

Show remaining 8" Front Port Pressure Vessels profiles (5)
Pressure Vessels
Knappe logo

Product profile

Feed assembly

This feed assembly is designed for RO membrane pressure vessels. It includes multiple EPDM O-rings for sealing.

Pressure Vessels
Knappe logo

Product profile

Serie 8"V2 70

This is a Knappe Series 8" V2 70 front-entry RO membrane pressure vessel designed for reverse osmosis applications.

Pressure Vessels
Knappe logo

Product profile

Permeat assembly

This is a Knappe Permeat assembly, the front endplate for RO membrane pressure vessels. It is rated for 1000/1200 PSI and includes EPDM O-rings for sealing.

Pressure Vessels
Knappe logo

Product profile

Feed assembly

This Knappe Pressure Vessels feed assembly is designed for RO membrane systems. It features EPDM O-rings and is rated for pressures up to 1200 PSI.

Pressure Vessels
Knappe logo

Product profile

Serie 8"V2 84

The Knappe Serie 8"V2 84 is an 8-inch, front-entry FRP seawater RO membrane pressure vessel.

Extra information

6 product profiles

Pressure Vessels
Knappe logo

Product profile

Knappe Catalog 8" Pressure Vessels

Knappe Catalog 8" Pressure Vessels are designed as RO membrane housings featuring the AnyClic self-sealing endplate and AnyDistance shimming system.

Pressure Vessels
Knappe logo

Product profile

Knappe AnyParts

These Knappe AnyParts are permeate port adapters designed for RO membrane housings. Available in various materials like PVC, PA66, PP, and SS 316L.

Pressure Vessels
Knappe logo

Product profile

Knappe AnyRack Single

The Knappe AnyRack Single is an RO membrane pressure vessel designed for water treatment applications.

Pressure Vessels
Knappe logo

Product profile

Knappe AnyRack Double

The Knappe AnyRack Double is a pressure vessel designed for RO membrane systems.

Pressure Vessels
Knappe logo

Product profile

Knappe Assembly & Operating Instructions 4 inch

This is a 4-inch front port composite vessel designed for RO/UF applications, built to ASME X code for brackish or seawater desalination. It features food-grade PVC, PPE.

Pressure Vessels
Knappe logo

Product profile

Knappe Assembly & Operating Instructions 8 inch

This composite vessel is designed for reverse osmosis, nanofiltration, and ultrafiltration applications, housing any make of 8-inch spiral-wound membrane elements.

Knappe Pressure Vessels Pressure Vessels | Models & Datasheets | AquaChain Guide