Dye Penetrant Inspection (DPI) Equipment

Wash-Off System

Air-Water Gun System With Gauges

Penetrant Wash Station System

The Penetrant Wash-Off System is an ideal way for organisations to guarantee compliance with NDT standards for their penetrant wash-off procedures. Perfect as both an addition to a new build penetrant line (including non-J&A branded ones) and a way to refurbish an older penetrant line.

Consisting of an Air-Water Control Box and electrical Water Heater unit, these items can be supplied either together as a complete solution or separately.


Air-Water Control Box

The Air-Water Control Box is mounted within a Stainless Steel housing and is supplied with a 12V stepdown box for low Voltage working safety in wet areas.

Intended to be mounted on the rear splash guard of a wash station, the Air-Water Control Box features 3 gauges for displaying water temperature, water pressure and air pressure. The gauges are all digital which make them easier to read than their analogue counterparts - Especially in the darkened conditions necessitated in fluorescent (type 1) penetrant processes.

Adjustable pressure regulators (air and water) and calibration socket points are also mounted on the front facia of the Air-Water Control Box for increased practicality. Each Air-Water Control Box is fitted with a Stainless Steel air-water wash-off gun and spiral hosing.

Pressure and temperature gauges are supplied calibrated with relevant paperwork issued by the Johnson & Allen Calibration Department. Calibrations are in keeping with national standards and are undertaken within the scope a quality management system assessed under BSI ISO 9001: 2015 with re-calibration services pricing available on request.

Air and water pressure guages measure and display pressures in units of PSI (default) but can swapped to guages that measure and display in units of bar instead upon request at placement of order.

Water Heater

A Water Heater unit is used avoid situations where the water supply feeding a penetrant line is too low. Too cold a temperature can negatively affect a penetrant process by altering properties such as the viscosity of a penetrant. In fact the average temperature of a mains supply is only 7°C, below the typical NAPCAP requirements of 10°C to 38°C.

The electrical Water Heater requires a 230V, 32A supply and is capable of 1°C incremental control up to a maximum temperature of 40°C.

The standard Water Heater is only suitable for a mains (tap water) supply. If your organisation is using demineralised water then Johnson & Allen should be made aware of this prior to quoting as the heating elements in the standard Water Heater are not suitable for this application.


Both the Air-Water Control Box and the Water Heater are easy to install with mounting brackets and commonly used pipe fittings. However if your organisation would like assistance our engineers are happy to visit and undertake this work if requested as part of the proposal.

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