What are the types of Filter Drain and when they should be used?

This article speaks on the various filter drains and it’s draining mechanics from compressed air systems. Draining contaminants from a distribution is a simple process but at times, it can be sophisticated.  

Constant Bleed Drain:

A Constant Bleed drain us used when the flow is too low to use an auto-drain, and when manual draining is not applicable. Constant Bleed drain functions by having a small hole in the bottom of the bowl, permitting condensate to be constantly removed.

Semi-automatic Drain

Semi-automatic drains is operated when the airline is depressurised. How it works? When the filter is pressurised, the drain can still operate manually by pushing the tube in the filter, which then projects outside the filter bowl.

Automatic Drain

An Automatic drain, a 2/2 valve functions by which is closes when the system is pressurised. The drain opens when liquid collects and causes the float to rise, and on depressurisation. Automatic Drains are good for when the filter location in the application makes access for servicing difficult, or for when equipment is in recurrent use and interruption for draining is not a favourite option.

Low-flow Drain:

A low-flow drain is used when the compressor capacity in the application is inadequate to close a number of standard automatic drains. Low flow drains are less operative at clearing contaminants, and hence should only be used when a semi-automatic drain or standard automatic cannot be used due to application.

‘Spitter’ Drain:

A Spitter drain is used when there is variance pressure between above the drain’s diaphragm and below it. How it works? The drain briefly lifts and ‘spits out’ the condensate collected under the drain. A ‘Spitter’ drain is well-matched to applications where there is rapid increases in flow, ensuing in difference pressure.

Drip-leg Drain:

A Drip-leg Drain protects distribution systems from damage or malfunctions. It functions to remove water that has acquired in the low points of a distribution pipework.