BVA300 Pneumatic Rotary Actuator

1. Safety information

These products comply with the ATEX Directive 94/9/EC wording in the source issue for use in potentially explosive atmospheres caused by a mixture of air, gases, vapours, mist or suspended dust within Group II, Category 2. Safe operation can only be guaranteed when the product is installed, commissioned, used and maintained by qualified personnel in compliance with the operating instructions. General installation and safety instructions for pipeline and plant construction, together with appropriate tools and safety equipment, must also be followed.

WARNING: do not service the actuator without first consulting the Installation and Maintenance Instructions. The end caps contain springs under load. The actuator must be vented before dismantling.

WARNING: if the valve has seized in a partly open position, the actuator springs may remain partly compressed and store significant energy. Follow the seized-valve dismantling procedure in the original guide before separating the assembly.

WARNING: the maximum air supply to the actuator and solenoid is 8 bar.

WARNING: when dismantling a seized valve assembly, connect a pressure-regulated compressed-air supply of 0 - 6 bar g (0 - 87 psi g) to air inlet port A and increase it gradually only until the valve stem just begins to rotate. Follow the complete seized-valve procedure in the original guide.

1.1 Intended use

Check the nameplate, this Installation and Maintenance Instructions document and the Technical Information Sheet to confirm that the product is suitable for the intended application. The source issue quotes the European Pressure Equipment Directive 97/23/EC and identifies actuator sizes up to and including BVA335 as SEP for the listed gas and liquid groups, while BVA340 and larger are shown in Category I. The source also states that the products were designed for compressed air and other high-purity Group 2 applications. Check material suitability, pressure and temperature and their maximum and minimum values. Where a product limit is lower than the system limit, provide a safety device against overpressure or overtemperature.

Determine the correct installation situation and orientation of the connected valve. Spirax Sarco products are not intended to withstand external stresses induced by the connected system; the installer must consider these stresses and take precautions to minimize them. Remove protection covers from connections and protective film from nameplates before installation on steam or other high-temperature applications.

1.2 to 1.10 Site and work controls

• Provide safe access and, where necessary, a guarded working platform. Arrange suitable lifting gear.
• Provide adequate lighting, especially for detailed or intricate work.
• Consider explosion risk, lack of oxygen, dangerous gases, temperature extremes, hot surfaces, fire, excessive noise and moving machinery.
• Consider the effect of isolation or electrical disconnection on the complete system. Operate isolation valves gradually to avoid system shocks.
• Isolate pressure and safely vent it to atmosphere. Consider double isolation and locking or labeling of closed valves. Never assume that a system is depressurized because a gauge reads zero.
• Allow temperature to normalize after isolation. Viton O-rings must not be exposed above 315°C (599°F), because toxic fumes may be released.
• Use suitable tools and consumables and only genuine replacement parts.
• Use protective clothing appropriate to chemicals, temperature, radiation, noise, falling objects and eye or face hazards.
• Use a permit-to-work system where applicable. Work must be carried out or supervised by a competent person.

1.11 to 1.16 Handling, residual hazards and disposal

Assess manual-handling risk for large or heavy products and use an appropriate handling method. In normal use the external surface may be very hot; at the maximum permitted operating conditions the source states that surface temperature may reach 200°C (302°F). The products are not self-draining, so take care when dismantling or removing them. Follow the safety information for the connected ball valve. Protect products from frost where they can be exposed below freezing.

Unless otherwise stated, the product is recyclable and no ecological hazard is anticipated when disposed of with due care. If Viton O-rings are fitted, follow the source disposal precautions for landfill, incineration and aquatic media. When returning products, provide written information about contamination residues, mechanical damage and any associated health, safety or environmental risk, including relevant safety data sheets.

2. General product information

2.1 Description

The BVA300 pneumatic actuator range uses a rack-and-pinion system that creates a linear torque with quarter-turn operation. The range is shown in Table 1.

2.1.1 Table 1: BVA300 series range

Double-acting: BVA310D, BVA315D, BVA320D, BVA325D, BVA330D, BVA335D, BVA340D, BVA345D, BVA350D, BVA355D, BVA357D, BVA360D and BVA365D.

Spring-return: BVA310S, BVA315S, BVA320S, BVA325S, BVA330S, BVA335S, BVA340S, BVA345S, BVA350S, BVA355S, BVA357S, BVA360S and BVA365S. BVA310S is available with /4, /6, /8, /10, /12 and /14 spring combinations; BVA315S through BVA365S are available with /8, /10, /12 and /14 combinations.

2.2 Standards for the BVA300 series

For actuator sizes up to and including BVA335, the source issue lists the European Pressure Equipment Directive 97/23/EC, Machinery Directive 89/392/EEC, ATEX Directive 94/9/EC Group II Category 2 for Zones 1, 2 and 21, 22, and EN 15714-3. For BVA340 and larger, it lists Category I Module A under the pressure equipment wording, the Machinery Directive, ATEX Group II Category 2 and EN 15714-3. Electrical and mechanical accessories are not covered by the actuator statement and require their own conformity assessment. The end user remains responsible for suitability of materials and design for the working conditions.

2.3 Technical data

2.4 Compressed air consumption and stroke time

The source charts give normal consumption in Nm³ per stroke and typical opening and closing times for the BVA310 to BVA365 sizes. The values below reproduce the chart values at the documented conditions; single-acting and double-acting columns must not be interchanged.

Normal consumption is stated for an open/close cycle when supplied with air at 6 bar g. The source notes that consumption is for BVA310 to BVA365 considering the spring configuration, and that the typical operating times use compressed air at 6 bar g and the documented spring configurations.

2.5 Inspection at delivery and storage

1. Examine every actuator on delivery for transport damage and inform the supplier immediately if damage is found.
2. Actuators are delivered closed as standard and contain the required number of springs for their type. An open-position configuration must be requested specially.
3. Store actuators under cover, protected from weather and dampness, with air inlets covered.
4. Do not unpack until installation except for the inspection described above.

2.6 Spring combination by actuator type

BVA300 pneumatic actuators use a maximum of seven identical pre-compressed springs on each rack. The spring quantity is identified by the suffix; for example, BVA3__S14 identifies 14 springs in total.

3. Installation

Before starting installation, observe the Safety information in Section 1. Refer to the Installation and Maintenance Instructions, body markings and Technical Information Sheet to check product suitability.

1. 3.1 Handling: transport and handle actuators with extreme caution, using suitable means for their size and weight. Check physical condition for damage during transport or handling.
2. 3.2 Limits: check materials, pressure, temperature and their maximum values. If the product maximum is lower than the system limit, provide a safety device to prevent overpressure.
3. 3.3 Access and lubrication: install with easy access for periodic inspection and maintenance. Actuators are lubricated during assembly and do not require further lubrication.
4. 3.4 Position: make sure actuator and valve are in the same open or closed position.
5. 3.5 Alignment: check alignment during and after assembly so that coupling parts work correctly aligned.
6. 3.6 Coupling bolts: tighten proportionally to distribute torque stress before fully tightening, whether the actuator connects directly or through a mounting bracket. Operate the actuator twice before fully tightening the coupling bolts.
7. 3.7 Travel stops: side stops provide plus or minus 5 degrees adjustment between 85 and 95 degrees. Loosening the locking nut adjusts the limits; one third of a locking-nut turn equals one degree of stroke. Do not adjust the manufacturer's setting by more than 2.5 degrees on each side or internal parts could be damaged.

3.3.1 Recommended minimum air quality

Actuators can be installed in line with the piping or at an angle of 90 degrees. Normal performance is to close clockwise and open anticlockwise, but this may be inverted easily.

3.3.2 Recommended tubing sizes

4. Commissioning

After installation or maintenance, ensure that the system is fully functioning. Carry out tests on alarms and protective devices.

5. Spare parts and maintenance

Before starting any maintenance programme, observe the Safety information in Section 1. Replacement parts must be genuine Spirax Sarco parts; otherwise any expressed or implied warranty is null and void.

5.1 Spare parts

The available spares for the BVA300D and BVA300S series are listed below. No other parts are supplied as spares. The BVA300D and BVA300S difference is the inclusion of springs within the end caps.

Order spares using the description in the source table and state the nomenclature of the pneumatic actuator. All listed spares are sold together in one spare-part kit. The source example is a BVA300 series maintenance kit with NBR O-rings for a Spirax Sarco BVA320S/08 pneumatic actuator.

5.2 Preventive maintenance

1. Carry out periodic inspection to check actuator function.
2. Operate actuators at least once every six months, or sooner where necessary.
3. Replace O-rings, guides and washers at the same time if necessary during maintenance.

5.3 Reasons for parts repair and replacement

Repair or replace parts as soon as leakage is detected through the upper or lower pinion O-ring, the piston O-ring or the end-cap O-rings. Replace all O-rings, bushings, slide guides and washers listed in the spare parts when the actuator is serviced.

5.4 Disassembly and reassembly

5.4.1 Precautions before disassembly

• Isolate and test the air and electrical supplies.
• Disconnect the actuator and accessories from air tubing and electrical wiring.
• Disassemble the solenoid from the actuator.
• Disassemble the actuator from the valve and/or couplings.

5.4.2 Disassembly

1. Remove the actuator end caps by loosening the external bolts. The source notes that spring-return cap bolts have adequate length for this operation.
2. Unfasten the nuts and remove the levelling screws.
3. Turn the pinion anticlockwise to disengage pistons in normally closed actuators, or clockwise in normally open actuators, and remove the pistons.
4. Remove the position indicator, slip washer, soft pinion washer and metallic pinion washer from the upper side.
5. Remove the pinion from the lower body by removing the upper pinion bearing and stop through the inside of the body.
6. Clean all parts and examine them for wear, including the inside of the cylinder.
7. If the parts are in good condition, replace the O-rings, bushings, slide guides and washers in the BVA300 maintenance kit before reassembly.
8. Lubricate with Molykote B 2-2 Plus grease and apply a thin layer to O-rings 7, 8 and 16.

5.4.3 Reassembly

1. Assemble all parts included in the genuine maintenance kit and lubricate where stated.
2. Place the pinion in the body from underneath; assemble the pinion stop and upper pinion bearing in their correct positions.
3. Install the soft pinion washer, metallic pinion washer, slip washer and position indicator in the upper part of the pinion.
4. Assemble both pistons and check that they engage at the same time when turning the pinion clockwise for normally closed or anticlockwise for normally open actuators.
5. Fit the end caps and tighten the bolts in sequence. Check that open and closed positions coincide with the position indicated on the pinion.
6. Operate the actuator several times and recommission the system.

6. Fault finding

Before dismantling the actuator, consult the instructions below.

6.1 Actuator with solenoid valve

If the actuator does not function, check that the valve is free to rotate, the actuator is correctly sized, the correct solenoid voltage is supplied and sufficient compressed air is available. If the voltage and pressure are correct and the valve is free, apply the correct voltage and listen for the solenoid click. If there is no sound, carefully remove the solenoid and observe the plunger when voltage is reapplied; replace the solenoid if it does not retract.

If the solenoid functions, remove it and the mounting block for a bench test with at least 3 bar g air supply and the correct voltage. When energized, air should flow from only one outlet port. If the actuator functions but leaks or loses power, check voltage is within 10% of the specified value, check for pressure drops during cycling, and replace leaking piston O-rings or a leaking spool valve as required.

6.2 Actuator without a solenoid valve

1. Make sure all ports are clear of obstructions.
2. Confirm that the actuator is lubricated and that no solidified grease is present between the pinion and piston racks. Clean, dry, regrease and reassemble if required.
3. Verify that the pinion shaft and pistons are not seized. Reassemble according to Section 5.4 if they are seized.
4. If there is excessive backlash, inspect piston-rack teeth for wear.
5. For spring-return actuators, check for misplaced or broken springs and inspect the body for scoring.
6. If the actuator and valve are free, reassemble and retest. Consult Spirax Sarco if the unit still fails to operate.