Describe, with the aid of a sketch, a pressure reducing valve suitable for supplying control air from the main starting air supply.(10)
A pressure reducing valve suitable for supplying control air from the main starting air supply.
Certainly, let’s outline the key characteristics of a pressure reducing valve suitable for supplying control air from the main starting air supply on a marine vessel:
Type of Valve:
- Pilot-Operated Pressure Reducing Valve: This type is commonly used in marine applications due to its accuracy, stability, and ability to handle high flow rates and pressure differentials.
Construction and Materials:
- Body: Typically made of cast iron, ductile iron, or bronze for strength and durability.
- Internal Trim: Stainless steel or other corrosion-resistant materials are used for the internal components like the valve seat, piston, and springs to withstand the compressed air environment and prevent corrosion.
- Diaphragm or Piston: A flexible diaphragm or piston separates the high-pressure inlet from the low-pressure outlet and controls the valve opening based on the downstream pressure.
- Pilot Valve: A small, built-in valve that senses the downstream pressure and controls the main valve’s opening to maintain the desired set pressure. 1. The Ultimate Guide to Pilot Operated Valves for Efficient Control Systems | THINKTANK cncontrolvalve.com
Operational Features:
- High Inlet Pressure Capability: The valve should be rated to handle the high pressure of the main starting air supply, typically in the range of 20-30 bar.
- Adjustable Outlet Pressure: The valve should have a provision for adjusting the outlet pressure to the desired level for control air, typically around 6-8 bar.
- Accurate Pressure Regulation: It should maintain a stable outlet pressure even with fluctuations in flow rate or inlet pressure, ensuring reliable operation of pneumatic control equipment. 1. Pressure Reducing Valves for Air – TLV www.tlv.com
- Large Flow Capacity: The valve should be sized to handle the maximum flow rate required by the control air system.
- Fail-Safe Operation: In case of a failure or loss of control air, the valve should fail in a safe mode, either closing to prevent overpressure in the control system or opening to vent excess pressure.
Additional Features:
- Filter/Strainer: A built-in filter or strainer may be included to protect the valve’s internal components from debris or contaminants in the compressed air.
- Pressure Gauge: A pressure gauge on the outlet side allows for monitoring the regulated control air pressure.
- Drain Valve: A drain valve at the bottom of the valve body allows for the removal of any condensate that might accumulate.
Why Pilot-Operated Pressure Reducing Valves are Preferred:
- Accurate and Stable Pressure Control: The pilot valve provides precise control of the main valve’s opening, ensuring a stable and accurate outlet pressure even with variations in flow or inlet pressure. 1. The Ultimate Guide to Pilot Operated Valves for Efficient Control Systems | THINKTANK cncontrolvalve.com
- High Flow Capacity: They can handle large flow rates required for control air systems.
- Good Sensitivity and Response: They respond quickly to changes in downstream pressure, maintaining consistent control.
- Reliable: They are generally reliable and require minimal maintenance.
Installation and Maintenance:
- Installation: The valve should be installed in the main air line, downstream of the air receiver and filters, and upstream of the control air distribution system.
- Maintenance: Regular inspection and cleaning of the filter/strainer and occasional servicing of the pilot valve might be required to ensure optimal performance.
By incorporating these features, a pilot-operated pressure reducing valve provides a safe, reliable, and efficient way to supply clean, dry, and regulated control air from the main starting air supply on a marine vessel.Sources and related content