Category: Industry Trends

Bi-directional travel stops

Adjustable stops on each end cap provide the flexibility of accurate valve rotation

positioning at the end of the ‘open’ and ‘close’ stroke. Both stops are located

on the cylinder centerline, the optimal osition to maximize travel adjustment

and eliminate any detrimental side loading on the travel stops.

Adjustable from 82° to 98°.

Ingress protection

Standard IP66. Optional IP68.

Spring designed for safety

All spring return models incorporate a ‘man-safe’ spring design that allows

the actuator to be safely assembled and disassembled in the field without

the need for special tools. The integral tie rods are bored and tapped to

provide a means of loading and unloading the spring in a safe andconvenient

manner.

DESIGNED WITH A HEART OF STAINLESS STEEL

Stainless steel yoke

The heart of any scotch yoke actuator is the yoke. S series actuators use

17-4PH stainless for this critical area as standard.

The yoke is the mechanism used to convert linear force to torque.

This area is most often where the life of the actuator is controlled.

Principles of construction

Using high quality materials of construction and modern rugged design

concepts provides the standard for high quality, low cost valve actuation.

The S actuator housings are all machined from 316 stainless steel castings.

This produces a rugged, low cost product through reduced machining time

and by eliminating wasteful excess material.

Any components that rotate or slide during operation, such as the high

strength stainless steel output shaft, stainless steel piston rod, stainless steel

thrust pin or the stainless steel piston, are all supported by replaceable friction

reducing bearings.

Double-acting and spring-return pneumatic quarter-turn

actuators for on-off and modulating control of valves in

heavy-duty service. Available for output torques to

1.000.000 Nm.

General Application

ALGA, ALGAS and ALGAS-QA pneumatic actuators are

designed for on-off or modulating control of quarter-turn

ball, butterfly, plug or damper style valves.

Features

• Totally enclosed, weatherproof housing in fabricated

carbon steel for maximum strength.

• Guide bar resists transverse loads and supports the

piston rod.

• Hard chromium plated alloy steel material guarantees

corrosion protection and minimal friction.

• Polytetrafluoroethylene (PTFE)-impregnated bronze or

sintered bronze bushings provide minimal friction and

extended service life.

• Scotch yoke design with canted or symmetric torque arm

allows close working to distinctive valve torque profiles.

• External travel stops for precise angular stroke

adjustment 90° ±4° at each end of travel.

• Electroless nickel plated and polished cylinder provides

maximum corrosion resistance and reduces friction.

• Floating type piston seals provide low hysteresis and

high sensitivity, preventing sticking problems.

• ALGAS spring-return pack incorporates up to four

springs, fully encapsulated in a factory welded cartridge

ensuring personnel safety and simplifying assembly.

• ALGAS spring action can be changed easily in the field

from to close to open or vice versa.

• Special coatings for offshore or corrosive environments.

Installation

The actuator can be mounted parallel or perpendicular to pipeline. The actuator can

be installed in any convenient position including vertical, horizontal or upside down.

1.Bolt mounting bracket to actuator hand tight. Do not tighten yet.

2.Install coupling on valve. Be sure rotary stops on valve are removed or

adjusted to allow actuator stops to do the stopping.

3.Install actuator and bracket to valve being sure to leave all fastener

connections hand tight. If possible, stroke valve and actuator to a half open

position 45° and physically shift actuator back and forth until coupling and

all fasteners are relaxed then tighten all bolts and nuts. This procedure will

accurately align valve stem to actuator output shaft and prolong valve stem

seal life. Lift the actuator at a balance point near the center housing. Do not

lift the weight of the valve, see Figure 1.

4.Cycle valve/actuator assembly and observe for smooth operation.

5.Adjust travel stops for perfect alignment in both open and closed positions.

NOTICE

If jackscrew override is installed, please refer to Section 3 for stroke adjustment.

6. Tubing connections – some models utilize two pistons for added power.

Spring-return (single-acting) dual cylinder designs require one “jumper”

to make the supply port common on both pistons. Double-acting (air to air)

dual cylinder designs require two “jumpers”. Refer to Figure 2 for

typical arrangement.

Electrostatic Charge

An electrostatic charge risk is present on the actuator surface; in case of cleaning,

use only antistatic cloth; in case of maintenance, avoid all rubbing/frictions that could

electrostatically charge the equipment.

Noise Emission

The verification of the noise of the actuated valve is at valve maker care.

The actuator’s noise can be considered negligible since it is an equipment for regular

on/off or intermittent use. If the integral quick exhaust valve is present, we

recommend using ear Personal Protective Equipment (PPE) to avoid any possible

acoustic discomfort.

The above mentioned accessories are operated by the actuator drive sleeve. The housing of the scotch

yoke mechanism has a flange with threaded holes to fix the actuator to the valve either

directly or, if required, with the interposition of an adaptor flange or a mounting

bracket. The actuator yoke has a hole with keyways suitable for the assembly of an

insert bush the internal hole of which is machined (by Biffi or at customer care),

according to the shape and dimensions of the valve stem. Biffi can supply different

types of control system following customer’s requirements.

Introducing the Actuator

The hydraulic actuator series OLGA-H was engineered and is manufactured to provide

maximum torque output with minimum supply pressure. The OLGA-H actuators

are suitable for any quarter turn application such as ball, plug, butterfly valves or

dampers, in both on/off and modulating heavy-duty service.

The actuator (see Figure 4) is made up of a weatherproof scotch yoke mechanism

transforming the linear movement of the pneumatic cylinder (on closing or opening)

into the rotary movement, which is necessary for operation. The angular stroke of

the yoke is adjustable between 82° and 98° by means of the external mechanical

stops screwed into the left wall of the mechanism housing and into the end flange

of the pneumatic cylinder. The cover of the scotch yoke mechanism is arranged

for the assembly of the required accessories (positioner, signalling limit switches,

position transducer, etc.) by means of proper matching units. The above mentioned

accessories are operated by the actuator drive sleeve. The housing of the scotch yoke

mechanism has a flange with threaded holes to fix the actuator to the valve either

directly or, if required, with the interposition of an adaptor flange or a mounting

bracket. The actuator yoke has a hole with keyways suitable for the assembly of an

insert bush the internal hole of which is machined (by Biffi or at customer care),

according to the shape and dimensions of the valve stem. Biffi can supply different

types of control system following customer’s requirements.