WASP W-20/W-25/ W-NAPFG Range

w 20A primary fuel filter/water separator providing protection from water and particulate commonly found in diesel fuel. Offering a cost effective range of primary filtration equipment for Marine, Industrial and Transport applications.





  • 20 and 150 micron cleaning
  • 3/8'' BSP connection
  • Plastic (clear), metal or plastic with metal heat shield bowls available.
  • 120 - 150 litres per hour flow rate
  • Lightweight and compact
  • Choice of separators- paper elements or long life stainless steel
  • LM6 grade aluminium filter heads with reversible stainless steel bracket & bolts
  • Powder coated aluminium filter heads for corrosion prevention & long service life
  • RINA (ISO10088) option available


How does it work?

1. Separation: 

The incoming flow of fuel oil changes velocity and direction, reducing the possibility of further reduction of any water droplets present through impact.

2.  Coalescence:  
This takes place on and just below the flow dispersion member allowing the separated water to descend to the bottom of the filter bowl.

3. Filtration:  
The fuel finally passes through the filter element to remove particulate.


Product Range

W-20 range Filtration (micron)                                                                       Details
W-20ST 20 micron paper Clear bowl
W-20STM 20 micron paper Metal bowl
W-25ST 150 micron stainless steel Clear bowl
W-25STM 150 micron   stainless steel Metal bowl
W-NAPFG-17T 150 micron stainless steel "Rina" spec clear bowl with metal heat shield (ISO10088)
W-NAPFG-17T-P 20 micron paper "Rina"   spec clear bowl with metal heat shield (ISO10088)

Spares and options

W-2301 Replacement seal kit
W-2302 Replacement 20 micron paper element and seal kit
W-2303 Replacement 150 micron stainless steel element only


Install/ Maintenance


A full range of fittings is available for easy installation.

  1. If necessary refit the two port plugs supplied with the filter. If they are not to be repositioned check they are correctly tightened.
  2. Follow the flow direction according to the arrows on each of the four ports.
  3. This range of filters should be installed on the suction side of the fuel supply system before the lift pump.


  • Check regularly for separated water
  • Drain off any separated water or impurities regularly via the thumb screw drain plug or valve
  • Remove clean and re-fit the stainless steel element as necessary
  • Replace seals and paper elements as required, see above spares

See the product support and servicing page

Technical Spec

Flow (L/h)
Port Size
3/8'' BSP
100 x 100 x 200mm
3/8'' BSP
100 x 100 x 200mm
3/8'' BSP
100 x 100 x 200mm
3/8'' BSP
100 x 100 x 200mm
3/8" BSP
100 x 100 x 200mm
3/8" BSP
100 x 100 x 200mm

Paper filter elements are 20 micron, Steel filter elements are 150 micron stainless steel. 

Water separation efficiency all models greater than 97%

Bowl capacities:

  • W-20 & 25 Series with cone fitted - 100ml
  • W-20 & 25 Series with element fitted - 75ml



Need help selecting a filter?

See our guide to help you select the most suitable filter for your needs.

Technical Support

How it works

See how the Separ filter works to separate water and particulate from fuel. 

SWK2000 flow diagram transparancy

How to Order

Call or email us to place your order. We accept ALL major credit and debit cards, bank transfer and also PayPal. 

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Expert advice

Unsure which spare parts you require? Or if a Separ filter will meet your requirements? 

Talk to our expert team. Call 01923 276 007



Delivery options

We have a wide range of shipping options available to suit your destination and budget.



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Contact Us

3 Kingley Park, Station Road, Kings Langley, Herts, WD4 8GW

Tel: +44 (0)1923 276007

Fax: +44 (0)1923 267463

Email: This email address is being protected from spambots. You need JavaScript enabled to view it.

Here to Help

Product guides

Fuel Specs


Selecting a Filter