Trevor Forster is Managing Director of Titan Enterprises. His experience in fluid handling dates back to the mid 1960’s when he started working on rotating seals and flow meter design for third party clients. Drawing upon over 40 years of using innovative design and production techniques to produce elegant flow metering solutions for organisations around the globe, in this feature – Trevor discusses flow meter IP ratings.

Flow Meter IP Ratings

A vast number of products quote IP code numbers. In terms of flow meter IP ratings, what do they actually mean?

Flow meter IP Ratings: The IP Code (or International Protection Rating, sometimes also interpreted asIngress Protection Rating*) consists of the letters IP followed by two digits and an optional letter. As defined in international standard IEC 60529 (edition 2.1), it classifies the degrees of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and liquids into electrical enclosures.

The standard aims to provide users more detailed information than vague marketing terms such as ‘waterproof’.

This IP standard is designed to cover all classes of equipment and most environmental considerations. Temperature is not covered within the standard as it is primarily concerned about physical ingress of anything that could harm the equipment or personnel. The tables below provides an introduction to the meaning of the relevant IP codes.

The first digit indicates the level of protection that the enclosure provides against access to hazardous parts (e.g., electrical conductors, moving parts) and the ingress of solid foreign objects.

Therefore, flow meter IP ratings specified as IP65 would denote a flow meter which is dust tight and capable of preventing any water ingress from a water jet from any direction. There are other limits set on these conditions and in the example given the jet is applied for three minutes. For the one metre submersion test the test time is 30 minutes. For further information relating to IP ratings please visit

The National Electrical Manufacturers Association (NEMA) also defines standards for various grades of electrical enclosures typically used in industrial applications. Each is rated to protect against designated environmental conditions.

A typical NEMA enclosure might be rated to provide protection against environmental hazards such as water, dust, oil or coolant or atmospheres containing corrosive agents such as acetylene or gasoline. A full list of NEMA enclosure types is available from the NEMA website –

Flow Meter IP Ratings

LevelObject size protected againstEffective against
0Not protectedNo protection against contact and ingress of objects
1>50mmAny large surface of the body, such as the back of the hand, but no protection against deliberate contact with a body part.
2>12.5mmFingers or similar objects.
3>2.5mmTools, thick wires, etc.
4>1mmMost wires, screws, etc.
5Dust ProtectedIngress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment, complete protection against contact.
6Dust TightNo ingress of dust, complete protection against contact.

The second digit indicates the level of protection of the equipment inside the enclosure against harmful ingress of water.

Flow Meter IP Ratings
LevelObject size protected againstEffective against
0Not protected
1Dripping waterDripping water (vertically falling drops) shall have no harmful effect.
2Dripping water when tilted up to 15°Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle up to 15° from its normal position.
3Spraying waterWater falling as a spray at any angle up to 60° from the vertical shall have no harmful effect.
4Splashing waterWater splashing against the enclosure from any direction shall have no harmful effects.
5Water jetsWater projected by a nozzle (6.3mm) against enclosure from any direction shall have no harmful effects.
6Powerful water jetsWater projected in powerful jets (12.5mm nozzle) against the enclosure from any direction shall have no harmful effects.
7Immersion up to 1mIngress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time (up to 1m of submersion).
8Immersion beyond 1mThe equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer. Normally, this will mean that the equipment is hermetically sealed. However, with certain types of equipment, it can mean that water can enter but only in such a manner that it produces no harmful effects.

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