Kelco D50 & D40 Level Switch CalibraƟon
The Kelco D50 and D40 level switches are factory calibrated to operate with the displacer or
displacers supplied with each switch. If required, the switch can be re-calibrated by adjusƟng
the calibraƟon screw located on the top deck of the switch. The calibraƟon screw is an M3 Allen
head stainless grub screw secured with a lock nut and sealed with red enamel.
D50 Level Switch
The D50 level switch is supplied with two displacers. If the D50 level switch fails to operate on
a falling level, that is, fails to switch when the falling water level uncovers the boƩom displacer
then the switch will require re-calibraƟon. It such a situaƟon unlock the calibraƟon screw lock
nut and wind the calibraƟon screw ¼ turn anƟclockwise and re-lock the lock nut. Test the switch
on a falling water level and ensure it operates properly. If it fails to switch, adjust the sensiƟvity
screw a further ¼ turn anƟclockwise and repeat the test.
If the switch fails to operate on a rising level, that is, fails to switch when the top most displacer
is covered by water it will require re-calibraƟng. Unlock the calibraƟon lock nut and turn the
calibraƟon grub screw ¼ turn clockwise and re-Ɵghten the lock nut. Test the switch on a rising
water level. If it fails to switch when the top displacer is covered by water, wind the calibraƟon
screw a further ¼ turn clockwise and repeat the test.
D40 Level Switch
The D40 level switch has a single displacer and switching must occur within the length of the
single displacer. When correctly adjusted the switch should change state at the boƩom edge of
the conical secƟon on a rising level and at the seam line half way down the straight secƟon on
a falling water level. If a rising water level fails to actuate the switch when the displacer is fully
submerged recalibrate the switch by adjusƟng the calibraƟon screw clockwise in ¼ turn steps
unƟl the switch operates at the correct point.
If the switch fails to operate on a falling water level adjust the calibraƟon screw anƟclockwise by
¼ turn and retest it. If required repeat the adjustment unƟl the switch operates properly.
Calibration adjustment screw and lock nut (M3)
