4
The media supplied to the regulator must be clean. Contamination can damage the seat
which may cause the regulator to fail. Filtration suited to the application is recommended
upstream of the regulator.
Should further assistance or information be required in relation to installation of any
Pressure Tech regulator please contact the office, giving reference to the regulators part
number and/or serial number.
3. Operation
Turning the hand wheel (or T-Bar) clockwise compresses the load spring, which in turn
opens the main valve, and allows the inlet pressure to pass through the orifice until the
outlet pressure is equivalent to the loading forces set by the compressed spring.
The LF-690 incorporates a segregated captured vent, which allows the outlet pressure to be
reduced whilst turning the hand wheel anti-clockwise. Excess pressure is vented off through
the ‘Vent’ port marked at the bottom of the regulator. This port should not be plugged or
blocked at any time.
The LF-690 series may be offered with pressure limiting, pressure locking or pre-set pressure
options:
Pressure limited regulators are fitted with locknuts on the adjusting mechanism in order to
limit the maximum allowable downstream pressure. Regulators fitted with pressure limiting
locknuts will state the limited pressure on the regulator label and this will also be indicated
in the part number.
Pressure locking regulators are fitted with a locking cap which may be set (when specified)
to pre-determined requirements. It is secured in place by three M5 grub screws which lock
against the bonnet of the regulator creating an anti-tamper device to ensure the pressure
cannot be adjusted accidentally.
Pre-set pressure regulators are adjusted (factory set) to specified customer requirements
within a given pressure range.
Both pressure locking and pre-set pressure regulators will be fully adjustable through a
given pressure range and the maximum allowable working pressures will be indicated on
the regulator label and in the part number.
*Note - A table is available on request defining allowable tolerances for set points within a
given pressure range.
