The gas feeder design shall be of the vacuum operated, solution feed type. The gas feeder shall be constructed of materials suitable for dry gas service. All springs used in the vacuum regulator shall be of tantalum alloy (stainless steel for ammonia). The rate valve and seat shall be solid silver (stainless steel for ammonia). A diaphragm shall be provided for vacuum regulation. The rate of gas feed shall be set manually and shall remain constant until manually changed. The gas shall flow at sonic velocity and a differential pressure regulator shall not be required.
The system shall be convertible to automatic control by insertion of a motorized control valve in the vacuum line to receive a signal from the appropriate control equipment.
The vacuum regulator shall mount directly on the container valve by means of a corrosion-resistant yoke assembly. spring-opposed inlet valve shall close tight upon loss of vacuum. Each vacuum regulator shall be equipped with a loss-of-gas indicator and a gas flowmeter. A spring-loaded diaphragm-actuated pressure relief valve integral to the vacuum regulator shall be provided to relieve gas pressure. The inlet capsule shall be a complete module, installed without the use of any tools.
The vacuum producing device shall be an ejector with a spring-loaded check valve to prevent flooding of the vacuum regulator or a CHLOR-A-VAC® chemical induction unit, Series 1420.
Automatic switchover shall be provided with automatic reset and integrally mounted vacuum regulator flow indicator.