One of the primary ways to acheive safety in any situation is to isolate power. In an electrical installation this can be a simple breaker or positive switch arrangement. With pneumatic equipment however, there must be consideration of not only isolation of supply power, but also the exhausting of stored downstream air pressure. The requirements will depend on the circumstances. In all cases, a proper risk assessment should be done.
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Standards for pneumatic energy isolation vary in different states, territories and countries however most stipulate the following requirements:
A simple LOX* valve can help acheive basic Lock Out & eXhaust. These are designed to be easy to identify & operate, and allow rapid exhausting of downstream air. They feature provision to fit a padlock and a visual pressure indicator. |
For larger installations, air isolation can be acheived remotely by air pilot or solenoid operation in addition to local manual operation and lockout.
For safety critical installaions, air isolation (and other circuit functions) is often required to meet more stringent requirements. In these circumstances, redundancy, monitoring, and electrical feedback may become necessary.
Where electrical feedback confirmation of an isolation valve's operation is required, there are options to suit various safety regimes.
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The SV27 series are a range of valves available in 2/2 or 3/2, air pilot or solenoid operated, which incorporate safety rated electrical switching for positional feedback. They are available in sizes up to 2 1/2" ports. |
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Double valves are a design which has 2 valve elements in a "redundant" formation so that either has the capability to perform the valve's function. There are various types & styles to suit a wide range of applications. The best performing control-reliable units offer fully dynamic onboard monitoring and memory. These are suitable for Control Category 4 applications. See also Press Safety Valves |
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Where a safety application demands a 4 way valve (5 port, 2 position configuration), it is often critical that if a fault occurs, the air presure will default to a specific port. The 77 series CrossMirror* valve offers double valve redundancy and directs pressure to port 2 (exhausting port 4) in the event abnormal operation is detected.
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In some cases it is important to have controlled re-application of air pressure after energy isolation. This is particularly true where gravity can affect equipment which is without air (eg. cylinders that may sag away from their normal rest position). In order to prevent violent jolting motion which could be dangerous or harmful to the machinery or personnel, an "ease-on" facility can allow gradual pressure build-up. An EEZ-ON* valve provides adjustable "soft start" ensuring all components return to their proper rest positions in an orderly fashion with minimal force and speed. EEZ-ON* valves are available as separate components or integrated with an exhaust capability & remote control, or a full LOX* capability. |
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Metal stamping presses are amongst the most dangerous of machinery. They have special safety requirements detailed in specific standards. These requirements are in addition to the more general safety requirements of other plant & machinery. Where many presses use a pneumatic valve to release the brake & engage the clutch to cycle the press, a special valve is needed. DM2 series valves incorporate a comprehensive array of design features to ensure press safety is simple and easy-to-acheive.
Ask about the new ROSS DM2 series double valves. Designed & built to comply with the world's newest international safety standards. |
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In many instances, safety can depend on the speed at which air is exhausted. Critical problems can result from undersized or dirt-clogged exhaust silencers which delay response times. In addition, noise associated with rapid high volume exhausting of air can cause safety and OHS issues. High flow anti-clog exhaust mufflers enable trouble-free operation for valves of all sizes. It is vitally important that safety circuits have correctly sized and fitted mufflers. |
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To protect against accidents & injuries caused by air hose whip, the hose fuze will detect a blown fitting and reduce airflow to a trickle. This also prevents wastage of air exhausting to atmosphere.
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Click here for the NEW Ross Safety Products Catalogue (Bulletin 510).
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