Pressure Connections; Vent; Changing Controller Action Or Mode; Throttling And On/Off Controllers - Emerson Fisher l2 Instruction Manual

Type L2

Pressure Connections

WARNING
Personal injury or property damage may
result from an uncontrolled process if
the supply medium is not clean, dry,
oil-free, or non-corrosive gas. Industry
instrument air quality standards
describe acceptable dirt, oil, and
moisture content. Due to the variability
in nature of the problems these
influences can have on pneumatic
equipment, Fisher has no technical
basis to recommend the level of
filtration equipment required to prevent
performance degradation of pneumatic
equipment. A filter or filter regulator
capable of removing particles 40
microns in diameter should suffice for
most applications. Use of suitable
filtration equipment and the
establishment of a maintenance cycle to
monitor its operation is recommended.
1. Provide a source of clean, dry air that meets the
requirements of ISA Standard S7.3 as the operating
medium. Refer to table 1 to determine supply
pressure.
2. Connect the supply pressure to the 1/4-inch NPT
female connection on the bottom of the controller
case.
3. Connect the output signal line to the equipment
being operated and to the 1/4-inch NPT output
connection on the top of the controller case.

Vent

WARNING
If a flammable, toxic, corrosive, or
reactive gas is to be used as the
supply pressure medium, personal
injury or property damage could
result from fire or explosion of
accumulated gas or from contact with
toxic, corrosive, or reactive gas. The
controller/actuator assembly does not
form a gas-tight seal, and when the
assembly is enclosed, a remote vent
line, adequate ventilation, and
necessary safety measures should be
used. A remote vent pipe alone cannot
4
be relied upon to remove all
hazardous gas. Vent line piping
should comply with local and regional
codes and should be as short as
possible with adequate inside
diameter and few bends to reduce
case pressure buildup.
The vent opening or the end of the remote vent
pipe, if one is required, must be protected against
the entrance of all foreign matter that could plug the
vent. Use 1/2-inch (13 mm) diameter pipe for the
remote vent pipe. Check the vent periodically to be
certain it is free of any obstructions.
Changing Controller Action or
Mode
WARNING
To avoid personal injury caused by a
sudden release of pressure, shut off
the supply pressure and bleed
pressure from the supply lines before
performing any procedure in this
section.
Throttling and On/Off Controller
The action of a throttling and on/off controller may be
changed between either direct or reverse, and the
control mode may be changed between either on/off
or throttling.
Refer to figure 3. Loosen the four switch retention
screws on the relay. Move the switches to the
control action and control mode required by the
application. Tighten the four switch retention screws.

Snap-Acting Controller

The action of a snap-acting controller may be
changed between either direct or reverse. The
control mode is always snap acting.
Refer to figure 4. Loosen the four switch retention
screws on the relay. Move the switches to the
control action required by the application. Tighten
the four switch retention screws.

Proportional Band Adjustment

Except where indicated, key numbers referenced in
the following procedures are shown in figure 8. The
span levers and other proportional band information
are shown in figure 5.
Instruction Manual
Form 5732
December 2001