Benefits

ISO 5211 - Interfaces between Valves and Actuators for Quarter-turn Movement

This standard lists the attachment dimensions for the interface between the Actuator/Valve or the Actuator/lntermediate Bracket/Valve. Brackets are bolted to the Valve mounting face, thus avoiding the need for keyways or dowels, as torque transmission is catered for by the compression force between the two components parts.

The attachment dimensions are listed against a maximum allowable transmitted torque value and are:

• The pitch diameter, number and size of attachment screws.
• A location spigot for alignment.
• The Actuator driver and driven Valve stem/adaptor dimensions.

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Indirect Mounting

Actuator sizing:

• There is a very wide range of outputs possible from any one size of pneumatic Actuator. The torque requirement of a single valve size can vary widely due to different seat materials and the nature, quality, pressure and temperature of the controlled medium. Pneumatic Quarter-turn Actuators are designed to operate safely in the Double Acting mode at the maximum pressure which is commonly 120 psi (8 bar). However as this pressure is seldom used in practice, the pressure normally chosen for the attachment features is the more common line pressure of 80 psi (5.5 bar) but can be as low as 30 psi (2 bar). Comparatively an 80 psi (5.5 bar) Double Acting mode Actuator will yield about seven times the end of stroke output of a similar size of Actuator used in the Spring Return mode at 30 psi (2 bar). However the Actuator must be designed to meet the most severe condition as the manufacturer has no control over possible usage. Therefore, the interface on the Actuator will be related to the torque generated in the Double Acting mode at a stated maximum pressure. (In the UK members of the British Valve and Actuator Manufacturers Association (BVAMA) must certify Actuators according to the BVAMA Code of Practice No 001/1292 for the torque output under stated test conditions.)

Gland adjustment:

• Some Valves have glands which require access for adjustment.

Maintenance and safety checks:

• Many plant operators insist on access to examine Valve Stem Seals and Stem function at frequent intervals and do not want them obscured.

Figure 3

This example shows a typical 4" reduced bore class 300 soft seated ball valve. The chart demonstrates how the actuator sizes can vary with a single valve size. In the example there are seven (7) different actuator models which use four different "ISO" flanges -
F07, F10, F12, F16

Low Quality Materials

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Essential Features

• The Mounting Bracket must be sufficiently rigid to transmit the given torque without twisting or imparting side loads or eccentric camming forces on the Actuator and Valve Stem Bearings.
  The whole automated assembly relies on correct alignment and adequate design to perform its full function efficiently and consistently. The Actuator drive must position the valve correctly and simultaneously signal this achievement via the switch box mounted on top of the Actuator. It follows that as much attention to detail is needed for mounting Brackets as is given to the selection of the Valve and Actuator.

Essential features for Adaptors

• The Adaptor fits in the drive train and compensates for the gap, introduced by fitting the Bracket, between the Valve stem and the female Actuator drive. Fig. 3 shows how the Actuator size can vary considerably within a single Valve size and the Adaptor is used to adapt the Actuator drive to the Valve stem. Most Actuator drives are female squares but many Valve stems are flatted (Double DEE) or keyed as well as square. The dimensions for these alternative drives are given in the ISO 5211 standard.
  Some Valve Stems have been made from high tensile material as the Valve torque requirements have been increased. This avoids major design changes to the Valve body but they are often smaller than the ISO 5211 preferred sizes. If the driving component is of material with a lower bearing stress limit than the stem this can lead to gradual wear, back-lash and possible failure.
  
  Care in the manufacture of Adaptors is also needed to prevent eccentricity which can introduce side loads and cause wear and malfunction to the Valve or Actuator. Users should also be sure that the Actuator sizing matches the Valve requirements. Too little torque can lead to incorrect Valve operation, too much may shear the Valve stem if the valve jams for any reason.
  The successful automation of Valves needs knowledge and experience. Hytork^® Valve Automation Centers bring this specialisation to the aid of users who are aware of the potentially high cost of shut down time and the possibility of dangerous incidents due to inadequate automation design.
  
  (In the UK, The British Valve and Actuator Manufacturers Association (BVAMA) have issued a Code of Practice No BVAMA 002/0393 entitled valve Actuator Mounting Kits.)

The NAMUR Solenoid Control Valve Interface

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The VDI/VDE 3845 Auxiliary Equipment Attachment

Benefits Of Standard Interfaces

Standard Interfaces for Automated Valve Assemblies Benefit Hytork^® Customers.

• Hytork^® Actuators and Accessories meet ALL the above standards.

• Provide lower assembled costs due to fewer package components.

• Provide engineered, rugged attachments of all components.

• Provide greater flexibility in the selection of components.

• Provide a more compact, rugged overall package.

• High Quality Hytork^® Mounting Brackets and Adaptors prevent damage to

• Valves and Actuators and save expensive downtime.

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Last Updated 11/14/08

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