A crown valve – also known as a block valve – is an essential part of an industrial steam boiler system that is used to regulate and slowly dissipate pressurized steam in a boiler. It can also be used to allow steam to escape the boiler and enter the piping system, providing heat, power or other steam functions. These boiler systems are often too large to be used anywhere except in an industrial plant. The crown valve gets its name from the location where the valve is provided on the boiler – directly on top, or crown, of the boiler unit.
Crown valves are also used as safety measures for boiler systems, as they have regulators that allow the escape of excess pressure that can build up if too long a period elapses between opening and closing the valve. The crown valve has indicators that allow the boiler operator to immediately identify whether the valve is open or not. Regulators also ensure that the status of boiler operation is visible from any vantage point. These types of valves are not considered continuous release valves or controlled release valves as crown valves must be either fully open or fully closed.
Early crown valves were typically made of cast iron, which made them very heavy and often unreliable. The cast iron would clump together under strong pressure, making the valve very difficult to open as pressure built up behind it. After steel and bronze crown valves became the standard for configurations where boiler units produced higher steam pressures, the introduction of steel and alloy crown valves quickly became the standard among many valve manufacturing methods. crown icon.
When a boiler operator is performing the task of opening or closing the crown valve of a boiler unit, the operator must exercise care and open or close the valve slowly and deliberately. Failure to do so can cause something called water hammer, which occurs when a large amount of steam pressure is released from the boiler too quickly and “reaches” the joints in the piping system. If the boiler unit is closed by the crown valve too quickly, a sudden increase in boiler pressure can occur, which can damage the connections in the boiler system. Most of the time, a secondary valve is installed in many high pressure systems to avoid any of these circumstances.