Recommended Opening Procedure: Air Products recommends that pressure seal valves be used in the fully open or back seated position. Opening the valve fully causes the lower stem to ride upward on its threads until it contacts the upper stem and mechanically drives the upper stems seal ridge into the packing ring. This improves the seal around the stem and helps to prevent packing leaks. Valves in the back seated position can be mistaken as closed by inexperienced or untrained operators. When an operator checks a valve to insure its position, he should always check by attempting to close the valve, never by trying to open the valve. If the valve was back seated using substantial effort, it is possible that the operator could think the valve is closed, when in fact it is fully open. Operators must be trained to use pressure readings or an equally reliable indicator to insure the cylinder valve is closed or open.

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