Automatic Crossover Valve Assemblies

Features and Benefits

MAC provides two basic automatic crossover valve systems, and can custom design others
to meet your requirements for use with HPOF
pipe type cable systems.

One assembly interconnects two independent cable systems in order to provide backup pressurization for one of the cables. The motor actuated valve is normally closed. If pressure in either cable system falls to a specified level, the motor actuated valve opens. The two cable systems are then tied together through flow limiters, which prevent the problem feeder from dragging down the pressure in the good cable. Should pressure continue to fall the motor actuated valve re-closes, isolating both systems.The second type of MAC crossover is designed for cable circuits normally connected hydraulically, such as two circuits connected for slow circulation. The automatic valve is open, and closes by operator command or automatically if there is a loss of control power, circuit breaker trip signal, or low pressure in either cable circuit.

Both types incorporate the following major elements:

• Factory fabricated piping and valving system, pre-tested and proven at 750 psig fluid pressure and full vacuum.
• Control system for manual or automatic operation
• Compact piping arrangement, which saves substation space without sacrificing ease of maintenance
• Fully insulated and heated enclosure, capable of stand alone installation.

Components are housed in a free standing NEMA Type 3R or 4 enclosure fabricated from painted steel, aluminum, stainless steel or molded fiberglass. Enclosure size, hydraulic design and the electrical system may be customized to your specifications.

High Pressure Gas Control Assemblies

Features and Benefits

MAC high pressure gas control and monitoring units connect to pressurized gas insulated cable and transformers, and provide for gas supply, local and remote pressure indication, testing connection points,
and alarm and circuit trip contacts.

Assemblies are housed in a NEMA Type 3R or 4 enclosure fabricated of painted steel, aluminum, stainless steel or molded fiberglass. They are available in small wall mountable configurations or larger, free-standing cabinets with space for multiple nitrogen gas cylinders or chart recorders.

Control units typically include four or five pressure switches for various alarm and cable circuit trip functions. Low and low-low cable pressure, low cylinder pressure, and high gas flow alarm contacts are available.
Other options include pressure transducers and recorders and a small annunciator.