June 2021
Installation, Operation and Maintenance Manual
MAN 689 Rev. 6
General Warnings
2
Section 1: General Warnings
1.2
Identification Plate
!
WARNING
It is forbidden to modify the information and the marks without previous written
authorization by Biffi Italia s.r.l.
The plate fastened on the actuator contains the following information (Figure1).
Figure 1
Data Plate
1.3
Description of the Actuator
ALGAS low pressure pneumatic spring-return, are suitable for the operation of quarter-turn
valves (ball valves, butterfly valves, plug valves) in both ON-OFF and modulating
heavy-duty service.
The actuator is made up of a weatherproof scotch yoke mechanism transforming the linear
movement of the pneumatic cylinder (or mechanical manual override, if foreseen) and of
the spring into the rotary movement, which is necessary for operation.
The spring-return pack incorporates up to four springs, fully encapsulated in a factory
welded cartridge: this ensures safety to personnel and simplifies assembly. The spring
action can be easily changed in the field from to close in to open or from to open in to close
(modular design).
The angular stroke of the yoke is adjustable between 82° and 98° by means of the external
mechanical stops screwed into the end flange of the pneumatic cylinder and into the end
flange of the spring-return pack . The cover of the scotch yoke mechanism is arranged for
the assembly of the required accessories (position-transmitter, signaling limit switches,
positioner, etc.) by means of proper matching units. The above mentioned accessories are
operated by the actuator drive sleeve.
The MHP hydraulic manual override is used to manually operate the actuator in lack of air
supply. The MHP unit consists of a hydraulic cylinder mounted on the end flange of the
pneumatic cylinder. The hydraulic control unit consists of: handpump, hydraulic check
valve, oil tank, relief valve and stop valve.