4.4.1 General. Actuator designs and material selection shall be compatible with the driver medium and operating pressures to which the actuator will be exposed.
The following three categories of actuator operating pressures and media are described in this standard: (1) oil-hydraulic actuator operating up to 2,500 psi (17.2 MPa) oil working pressure, (2) pneumatic actuator operating up to 150 psi (1.03 MPa) air pressure, and (3) water-hydraulic actuator operating up to 150 psi (1.03 MPa) water
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Approved by American National Standards Institute: May 21, 2002.
Copyright © 2003 American Water Works Association, All Rights Reserved.
Approved by American National Standards Institute: May 21, 2002.
POWER-ACTUATING DEVICES 13
pressure. Water-hydraulic actuator may also be used for hydraulic oil up to 150 psi (1.03 MPa) provided the seals are compatible with the oil to be used and no adverse effects will be generated with nonmetallic construction materials.
4.4.2 Materials. All materials designated herein, when used in actuators produced according to the provisions of this standard, shall conform, at a minimum, to the requirements designated in Sec. 4.4.2.1 or each material listed. When reference is made to ANSI, ASTM, or other standards, the latest revision thereof shall apply.
Other materials may be used if specifically accepted by the purchaser.
4.4.2.1 Physical and chemical properties. Materials shall be in conformance with the physical and chemical requirements of this subsection as follows:
4.4.2.1.1 Cast iron. ASTM A126 class B or ASTM A48 class 40, minimum.
4.4.2.1.2 Ductile iron. ASTM A536 grade 65-45-12 or 60-40-18 or 80-60-08, or ASTM A395 grade 60-40-18.
4.4.2.1.3 Alloy cast iron. ASTM A436 type 1 or type 2, or ASTM A439 type D2.
4.4.2.1.4 Stainless steel. ASTM A276 type 304 or type 316, or ASTM A743 grade CF8 or CF-8M, or ASTM A351 grade CF8 or grade CF-8M.
4.4.2.1.5 Nickel–copper alloy. ASTM B127 or ASTM B164.
4.4.2.1.6 Carbon steel. ASTM A108.
4.4.2.1.7 Cast steel. ASTM A216 grade WCB.
4.4.2.1.8 Fabricated steel. ASTM A36, ASTM A516, or better.
4.4.2.1.9 Brass or bronze. Components of brass or bronze shall be made to ASTM standards or the uniform numbering system (UNS) and shall have a minimum yield strength of 14,000 psi. Any bronze alloy used in the cold-worked condition shall be capable of passing the mercurous nitrate test in accordance with ASTM B154 to minimize susceptibility to stress corrosion. Because of dezincification considerations all bronze parts subject to water contact shall contain not more than 7 percent zinc. All aluminum–bronze parts subject to water contact shall be inhibited against dealuminization by receiving a temper anneal at 1,200°F (650°C) ±50°F (28°C) for 1 hr per in. (25.4 mm) of section thickness followed by cooling in moving air or by water quenching.
4.4.2.1.10 Zinc Alloy. ASTM B-240.
4.4.2.1.11 Aluminum. ASTM B179, Alloy 356.6 (UNS A03561).
4.4.2.1.12 Aluminum. ASTM B85.
14 AWWA C540-02
4.4.3 Oil-hydraulic cylinders. Oil-hydraulic cylinders shall be of tie-rod, bolted-flange, or welded construction and suitable for operating pressures up to a maximum of 2,500 psi (17.2 MPa). Minimum burst pressures shall be 10,000 psi (68.9 MPa).
The purchaser shall select appropriate oil-hydraulic cylinders of tie-rod, bolted-flange, or welded construction, according to the rated operating oil pressure of the system designed. Cylinder mounting dimensions shall comply with applicable requirements of ANSI B93.29 regarding mountings and physical dimensions with modifications where required to adapt to the valve or slide gate actuator’s cylinder mounting. Cylinder pressure ratings shall be determined per ANSI B93.10. The hydraulic cylinders shall be those catalogued by power-cylinder manufacturers certifying that the selected cylinders comply with the above ANSI standards with modifications noted. No special corrosion-protection coatings or corrosion-resistant materials shall be required unless specified by the purchaser. Corrosion-resistant materials, if required, shall be corrosion-resistant metal or nonmetallic material.
4.4.3.1 Seals. All static and dynamic seals shall be pressure energized and shall be compatible with the hydraulic fluid to be used.
4.4.3.2 Component suitability. Descriptions of components for oil-hydraulic cylinders are not listed in detail in Sec. 4.4.4, 4.4.5, or 4.4.6. Purchasers of oil-hydraulic cylinders may choose to consider materials in Sec. 4.4.2 and provide specifications on individual components of oil-hydraulic cylinders.
4.4.4 Water-hydraulic cylinders. Water-hydraulic cylinders shall be of tie-rod or bolted-flange construction and shall have a pressure rating of 150 psi (1.03 MPa) minimum, as determined by ANSI B93.10. Cylinder mounting dimensions shall comply with ANSI B93.29 regarding mounting and physical dimensions with modifications where required to adapt to the valve or slide gate actuator’s cylinder mounting. Construction materials shall be selected to ensure adequate corrosion resistance with a design safety factor of 4:1 based on tensile strength.
4.4.4.1 Cylinder barrels. Cylinder barrels shall be bronze, fiberglass-reinforced plastic, or stainless steel. The inside surface of the barrel shall have a 20-microinch (0.508-µm) finish or smoother.
4.4.4.2 Heads and caps. Heads and caps shall be bronze, suitable nonmetal-lic material, ductile iron, or steel. Steel or ductile-iron components shall have all surfaces plated. The plating shall withstand a salt-spray test of not less than 144 hr in accordance with ASTM B117.
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Approved by American National Standards Institute: May 21, 2002.
Copyright © 2003 American Water Works Association, All Rights Reserved.
Approved by American National Standards Institute: May 21, 2002.
POWER-ACTUATING DEVICES 15
4.4.4.3 Cylinder pistons. Pistons shall be bronze, suitable nonmetallic mate-rial, stainless steel, cast iron, ductile iron, or steel. Steel, cast iron, or ductile iron shall be plated. Plating shall withstand a salt-spray test of not less than 144 hr in accordance with ASTM B117.
4.4.4.4 Piston rod. Piston rods shall be 30,000-psi (206.8-MPa) minimum yield strength, stainless-steel hard chrome plated 0.0005-in. (0.0127-mm) thick, and shall have a 20-microinch (0.508-µm) finish or smoother.
4.4.4.5 Piston-rod bushing. Bushings shall be bronze or nonmetallic materi-als suitable for water service and having a bearing capacity of 1,500 psi (10.3 MPa) minimum.
4.4.4.6 Rod seals. Seals shall be nonmetallic elastomeric materials suitable for water service. Rod seals shall be of a pressure-energized design.
4.4.4.7 Piston seals. Seals shall be nonmetallic elastomeric materials suitable for water service. Piston seals shall be of a pressure-energized design.
4.4.4.8 Tie rods. Rods shall be carbon steel, cold rolled, with a minimum yield strength of 60,000 psi (413.7 MPa).
4.4.5 Pneumatic cylinders. Pneumatic cylinders shall be of tie-rod or bolted-flange construction with a pressure rating of 150 psi (1.03 MPa) minimum. Cylinder mounting dimensions shall comply with applicable requirements of ANSI B93.15 regarding mountings and physical dimensions with slight modifications where required to adapt to the valve or slide gate actuator’s cylinder mounting. Cylinder pressure ratings shall be determined per ANSI B93.10. However, AWWA C540 is not restricted to such a cylinder category provided the following materials are used with an adequate design safety factor of 4:1.
4.4.5.1 Cylinder barrels. Barrels shall be bronze, fiberglass-reinforced plastic, carbon steel, stainless steel, or hard-drawn brass. The inside surface of the barrel shall have a 20-microinch (0.508-µm) finish or smoother. If carbon-steel material is used, the inner surface shall be hard chrome plated 0.0005-in. (0.0127-mm) thick or electroless nickel plated to the same thickness.
4.4.5.2 Heads and caps. Heads and caps shall be carbon steel, suitable nonmetallic material, or ductile iron. All surfaces, except nonmetallic material, shall be chrome- or cadmium-plated if specified by the purchaser.
4.4.5.3 Cylinder pistons. Pistons shall be stainless steel, carbon steel, suit-able nonmetallic material, cast iron, or ductile iron. All carbon-steel, cast-iron, or ductile-iron surfaces shall be chrome- or cadmium-plated if specified by the
16 AWWA C540-02
purchaser. Metallic pistons shall not be used with nonmetallic cylinder bodies unless nonmetallic wear strips are provided.
4.4.5.4 Piston rod. Piston rods shall be 30,000 psi (206.8 MPa) minimum-yield-strength carbon steel or stainless steel. Both materials shall be hard chrome or electroless nickel plated 0.0005-in. (0.0127-mm) thick and having a 20-microinch (0.508-µm) finish or smoother.
4.4.5.5 Piston-rod bushing. Piston-rod bushings shall be iron, bronze, or a nonmetallic material suitable for air service.
4.4.5.6 Rod seals. Rod seals shall be elastomeric materials suitable for air service and designed to be pressure energized.
4.4.5.7 Piston seals. Piston seals shall be elastomeric materials suitable for air service. Piston seals shall be of a pressure-energized type.
4.4.5.8 Tie rods. Tie rods shall be carbon steel, cold rolled, with a minimum yield strength of 60,000 psi (413.7 Mpa).
4.4.6 Nonmetallic water-hydraulic and pneumatic cylinders. No n m e t a l l i c water-hydraulic and pneumatic cylinders shall be of tie-rod construction and shall have a pressure rating of 150 psi (1.03 MPa) minimum. Construction materials shall be selected primarily on the basis of corrosion resistance and also on the basis of water absorption, creep, and mating-surface compatibility. Such components and materials selected shall have a minimum safety factor of 4 at the 150-psi (1.03-MPa) pressure rating. Furthermore, materials selected shall have a maximum water absorption of 2 percent after 24 hr in a 1/8-in. (3-mm) thick section when tested per ASTM D570.
4.4.6.1 Cylinder barrels. Cylinder barrels shall be fiberglass-reinforced plas-tic having an inside surface finish of 20 microinches (0.508-µm) or smoother. No fiberglass strands shall extend to the inside surface.
4.4.6.2 Heads and caps. Heads and caps shall be molded or machined from high-modulus thermoplastic, thermoset, or laminated phenolic materials. Fixed-mounted cylinders shall be attached to the valve or slide gate operating mechanism using plated or corrosion-protected coated steel plates (as described in Sec. 4.5) retained to the cylinder proper using tie rods. Pivot-mount cylinders shall be attached to the valve or slide gate operating mechanism using plated or corrosion-protected coated clevis or trunnion plates retained to the cylinder proper using tie rods. Such metallic plates or clevis shall be external to water passages in the cylinder.
Copyright © 2003 American Water Works Association, All Rights Reserved.
Approved by American National Standards Institute: May 21, 2002.
Copyright © 2003 American Water Works Association, All Rights Reserved.
Approved by American National Standards Institute: May 21, 2002.
POWER-ACTUATING DEVICES 17
4.4.6.3 Cylinder pistons. Cylinder pistons shall be molded or machined from high-modulus thermoplastic, thermoset, or laminated phenolic materials.
Particular attention shall be paid to ensure that the materials selected do not have excessive water absorption or lack dimensional stability.
4.4.6.4 Piston rods. Piston rods shall be 30,000 psi (206.8 MPa) minimum yield strength, stainless-steel, hard chrome plated, 0.0005-in. (0.0127-mm) thick, having a 20-microinch (0.508-µm) finish or smoother.
4.4.6.5 Piston-rod bushings. Piston-rod bushings shall be bronze or nonme-tallic materials suitable for water service and having a high bearing capacity of l,500 psi (10.3 MPa) minimum.
4.4.6.6 Rod seals. Rod seals shall be elastomeric materials suitable for water service and designed to be pressure energized.
4.4.6.7 Piston seals. Piston seals shall be elastomeric materials suitable for water service. Piston seals shall be of a pressure-energized design.
4.4.6.8 Tie rods. Tie rods shall be cold-rolled, zinc-plated carbon steel or stainless steel. Either material shall provide a minimum yield strength of 60,000 psi (413.7 MPa).
4.4.6.9 Material selection confirmation. Prior to the proof-of-design tests outlined in Sec. 5.2.3, nonmetallic-material cylinders shall undergo the following additional tests to demonstrate proper material selection.
4.4.6.9.1 Water absorption effects. Each cylinder to be tested shall be subjected to 150-psi (1.03-MPa) water pressure at both cylinder ports for a period of 30 days. At the conclusion of the 30 days, the cylinder shall be cycled back and forth 10 times with no more than 7-psi (48-kPa) water pressure being used for the full cycle.
4.4.6.9.2 Modulus effects. If the same nonmetallic-design cylinders are to be used for both water-hydraulic and pneumatic service without any changes, the cylinder shall be tested as a pneumatic unit at 150-psi (1.03-MPa) air pressure for 5 min. No leakage shall be allowed across the piston in either direction with the piston retained at midstroke.
4.4.7 Driver media.
4.4.7.1 Scope. This section describes the minimum quality of driver media to be provided by the purchaser for actuators of the pneumatic, water-hydraulic, and oil-hydraulic types for valves and slide gates in open–close, throttling, and
18 AWWA C540-02
modulating service. Driver media includes air for pneumatic actuators, water for water-hydraulic actuators, and oil for oil-hydraulic actuators.
4.4.7.2 Properties described. This standard describes physical, chemical, and temperature/pressure suitability of the driver medium to actuator components and to the positioner, where applicable, so as to minimize potential damage to those components. Physical properties relate to foreign matter, such as scale and dirt, and to undesirable trace contaminants, such as water vapor and oil mist. Chemical properties relate to corrosion deterioration caused by aggressive chemicals, low pH conditions, and excessive dissolved minerals (for example, scaling damage from very high hardness in water medium). Temperature/pressure properties relate to operating problems or material damage caused by excessively high or low temperature or pressure of the medium.
4.4.7.3 Pneumatic-medium requirements.
4.4.7.3.1 Physical.
1. For open–close service. Compressed air shall have dirt and scale particles and water droplets removed to no larger than 40 µm (1.6 mils). It is recommended that the purchaser provide air-line lubricators for an open–close actuator unless otherwise indicated by the actuator manufacturer.
2. For throttling or modulating service (with positioner). Compressed air shall have dirt and scale particles and water droplets removed to no larger than 5 µm (0.2 mils). Factory prelubrication of the actuator shall be provided by the actuator manufacturer unless otherwise specified. It is recommended that the purchaser provide air-line filters to remove oil-mist droplets to no larger than 5 µm (0.2 mils) for protection of the positioner. The use of air-line lubricators should be avoided.
3. The purchaser should ensure that water vapor is removed from the compressed air to a dew-point temperature below that of the lowest ambient temperature surrounding the actuator and positioner.
4.4.7.3.2 Chemical. Compressed air free of harmful chemicals shall be used unless otherwise specified. Nonreactive gas (such as nitrogen) may be used in lieu of compressed air if so specified by the purchaser.
4.4.7.3.3 Temperature/pressure. Compressed-air temperatures up to 130°F (54.4°C) and pressures up to 150 psi (1.03 MPa) shall be used unless otherwise specified.
4.4.7.4 Water-hydraulic medium requirements.
Copyright © 2003 American Water Works Association, All Rights Reserved.
Approved by American National Standards Institute: May 21, 2002.
Copyright © 2003 American Water Works Association, All Rights Reserved.
Approved by American National Standards Institute: May 21, 2002.
POWER-ACTUATING DEVICES 19
4.4.7.4.1 Physical. Hydraulic-water medium shall have dirt and scale parti-cles removed to no larger than 20 µm (0.8 mils).
4.4.7.4.2 Chemical. Clean water of potable quality having a salinity not greater than 500 mg/L and a total hardness not greater than 300 mg/L (as CaCO3) shall be used unless otherwise specified. For potentially aggressive (low-alkaline) waters, a water analysis that includes total hardness, pH, CO2, and conductivity should be made and included in the purchaser’s specifications.
4.4.7.4.3 Temperatures/pressure. Hydraulic-water temperatures up to 125°F (51.6°C) and pressures up to 150 psi (1.03 MPa) shall be used unless otherwise specified.
4.4.7.5 Oil-hydraulic medium requirements.
4.4.7.5.1 Physical. Hydraulic oil shall have dirt and scale particles and water droplets removed to no larger than 10 µm. Viscosity of hydraulic oil shall be 135 to 165 SSU (Standard Saybolt Universal) at 100°F (37.8°C) unless otherwise specified.
4.4.7.5.2 Chemical. Hydraulic oil shall be used unless otherwise specified.
Where an alternative oil medium is intended, the purchaser should clearly specify its characteristics.
4.4.7.5.3 Temperature/pressure. Hydraulic-oil temperatures up to 200°F (93.3°C) and pressures up to 2,500 psi (17.2 MPa) shall not be exceeded unless otherwise specified. When hydraulic oil is used with water-hydraulic-type cylinders, pressures of 150 psi (1.03 MPa) and temperatures of 130°F (54.4°C) shall not be exceeded.
4.4.8 Quarter-turn cylinder actuators. For operation of quarter-turn valves, an intermediate mechanism is required to convert a cylinder’s linear output to the required rotary motion. Acceptable methods of conversion are lever, link/lever, rack and pinion, and scotch yoke. Pneumatic quarter-turn rotary vane-type actuators need no intermediate mechanism. Each design has inherent advantages that should be reviewed by the purchaser.
4.4.8.1 General requirements. The actuator shall include a rigid housing or structure for mounting to the valve and supporting the cylinder. Housings, supports, and connections shall be designed with a minimum safety factor of 5, based on the ultimate strength, or a minimum safety factor of 3, based on the yield strength of materials used. Linkage shall contain an adjustment for setting the valve in the closed position.
20 AWWA C540-02
4.4.8.2 Bearings. All moving surfaces shall be supported by anti-friction bearings. A bearing of corrosion-resistant metal shall be provided on the shaft outboard of the valve shaft seal or in the actuator housing to protect the valve shaft seal from side thrust forces developed in the operating mechanism.
4.4.8.3 Lubrication. Housings shall contain seals to prevent the leakage of lubricant regardless of position. Lubricants shall be suitable for year-round service based on prevailing ambient temperature conditions.
4.4.8.4 Handwheel. Optional handwheels shall be so connected that opera-tion by the actuator shall not cause the handwheel to rotate. Operaopera-tion of the handwheel will assume loss or isolation of power to the actuator. The handwheel shall require a maximum actuator input force of 80 lb (356 N) on the rim at any point through valve travel. The handwheel shall have an arrow and the word
“OPEN” integrally cast or permanently affixed indicating the direction to open the valve.
4.4.8.5 Position indication. Position indication shall be accomplished using an indicator dial or arrow.
4.4.8.6 Stop limiting devices. Valve actuators shall be equipped with adjust-able, mechanical, stop limiting devices to prevent over-travel of the valve in the open and closed positions.
4.4.9 Pneumatic quarter-turn vane-type actuators. Pneumatic quarter-turn rotary actuators shall be of the vane-type design with a minimum operating pressure rating of 150 psig (1.03 MPa).
4.4.9.l Actuator housing. Housing shall be of aluminum construction. The interior and exterior surfaces of the housing shall be fusion-bonded epoxy.
4.4.9.2 Vane construction. Vane shall be of carbon steel construction and shall be electroless nickel plated. Vane and output shafts shall be of one (1) piece design.
4.4.9.3 Actuator output shafts. Actuator output shafts shall include Teflon-impregnated bronze bushings backed by steel.
4.4.9.4. Vane seals. Vane seals shall be of a material suitable for air. Seal housing contact shall be accomplished by using seal expanders. Seal expanders shall be constructed of stainless steel to prevent corrosion on interior of actuator. Vane seals shall seal both sides of the vane to isolate output shaft. No compressed air or fluid shall be allowed at the output shaft.
Copyright © 2003 American Water Works Association, All Rights Reserved.
Approved by American National Standards Institute: May 21, 2002.
Copyright © 2003 American Water Works Association, All Rights Reserved.
Approved by American National Standards Institute: May 21, 2002.
POWER-ACTUATING DEVICES 21
4.4.9.5 Hardware. All stop screws and all case bolts and nuts shall be stainless steel.
4.4.10 Hydraulic/pneumatic actuator application.
4.4.10.1 Operating pressures. Operating pressures with either a hydraulic or pneumatic medium shall be maintained on the actuator driver mechanism at each end of its stroke unless other means are provided to prevent actuator drifting.
4.4.10.2 Adjustable flow-control device. When specified by the purchaser, actuators shall be equipped with adjustable flow-control devices at or near each port of the actuator controlling the operating medium exhausting from the actuator.
Unless otherwise specified by the purchaser, the opening and closing speeds shall be nominally set for a range of 30 sec to 60 sec. However, the maximum operating time for pneumatic actuators without slave cylinders should be limited to not more than 5 sec per in. of stroke to avoid jerky operation. Final adjustments shall be made by the purchaser to minimize line surges during normal operation.
4.4.10.3 Actuator requirements. Pneumatic and water-hydraulic actuators shall not require more than 7-psi (48-kPa) pressure to cycle a complete stroke in each direction before being connected to a valve or slide gate operating mechanism. Oil-hydraulic actuators shall not require more than 15 psi (103 kPa) for the same type of cycling.
4.4.10.4 Rod-seal protection. Actuators shall be equipped with externally facing dirt wipers to protect the rod seals from dirt and other foreign materials. The
4.4.10.4 Rod-seal protection. Actuators shall be equipped with externally facing dirt wipers to protect the rod seals from dirt and other foreign materials. The