Before power up the device to proceed with calibration
carefully read the following safety warnings.
– Comply with current national and local
regulations for electrical installation work.
– Must be installed and put into service in
conformance with EN 60079-14 and / or
national and local regulations applicable for
– Before carrying out any work on the device,
power off the instrument or make sure
that the local conditions in the potentially
explosive atmosphere permit- the safe
opening of the cover.
– Connect the wires to the instrument's
terminals, taking care of complying with
polarities and maximum voltage allowed.
– Before power up or after doing any work on
the device always check the cover (12) is fully
screwed, O-ring (10) is free of any damage
and security screw (9) is well locked.
8.1 Calibration of rotary limit switch
496-.57 and 496-.58 equipped with
• The concave portion of the lever (5) must be strictly
concentric to the cam (13) when the micro-switch is
© 2018 Baker Hughes, a GE company. All rights reserved.
• This is an important caution to make sure the lever is
properly depressed when not actuated.
• If not, loosen the screws (3 & 17) and slightly move
the lever upwards or downwards. Tighten the screws.
• Slightly loosen the cam locking screw (1) using a
3/32" socket hex head wrench.
• Move the plug stem to the position required to
actuate the switch.
• It is important to note that the cam operating the
right hand micro-switch must actuate the lever (5) at
the end of the counterclockwise rotation. (See detail
• This makes sure the screw (2) has free the lever (5)
when the valve is throttling. The remaining concave
portion only ensures micro-switch actuation in case
of over travel. Conversely, the cam operating the left
hand micro-switch must actuate the lever (5) at the
end of the clockwise rotation. (See front view below).
• To meet the above requirement when only one
micro-switch is provided (type 496-158) it may
be necessary to change the location of the
• Rotate the cam (13) until the micro-switch is
actuated. Lock the cam (13) tightening the screw (1).
• Fine tune adjustment with screw (2). Use a 1/16"
socket hex head wrench. The screw (2) must come
out the cam enough to properly depress the lever (5).
• Strictly follow safety instructions under §7.4 before
putting into service.
496 Series Masoneilan Position Transmitter ATEX Instruction Manual | 15