When asked about the possible difficulties of a pressure reducing valve, it is convenient to start by providing a brief explanation about its operation before getting to the point. It is worth clarifying that this is a very frequent question among people who already have parts of this type in their equipment or among those who are considering acquiring one.
Also called “pressure regulators”, these are hydraulic control valves, whose set point is to reduce a high pressure upstream of the valve to a lower constant value downstream of the valve, regardless of upstream pressure variations and variations in flow or demand on the line.
The 5 most repeated problems with the pressure reducing valve
The use of steam in any manufacturing process is very efficient and economical, but if the parts that process the steam are not working at their optimal capacity, this could produce an extra cost that would ruin, with what was once thought as an efficient use of resources. If you are using such a part, here are the main problems that can arise with the pressure reducing valve.
Controlled pressure is triggered under normal load conditions
This could mean that something is preventing the valve from closing tightly during normal operating conditions. There are two main causes for your pressure reducing valve to fail due to controlled excess pressure under normal load conditions:
Dirt or foreign material has got between the pilot valve seat and the head.
Foreign particles have been introduced between the head and the seat of the main valve.
To solve this problem, you must inspect and clean the space between the head and the seat. We also recommend that you ensure that the pressure detection line is not obstructed by removing, inspecting and cleaning the holes and pipes.
Controlled pressure is exceeded only with light loads
There are four main reasons why your pressure reducing valve can fail due to overtrip under light load conditions:
The head and seat of the main valve may be worn or there may be dirt between them. To fix it, inspect and clean the valve head and seat.
The valve may be very oversized. In this case, you need to proceed to repair the part.
The bypass valve does not close tightly or leaks. As in the previous case, you need to check and repair the part.
There is dirt or foreign material on the stem and guide of the main valve. To fix this, you will need to remove, inspect and clean the parts.
Pressure reducing valve fails to open
There are six main reasons why the valve may not open. Here we share each of the reasons, along with their solution:
The main valve is broken: unscrew the copper tube connection and break the bypass valve. If steam comes out of the main valve diaphragm housing, the diaphragm is defective and needs to be replaced.
The hole is clogged: remove and clean.
The pilot valve seat is clogged with dirt: remove the head and seat assembly, and inspect and clean or replace.
The sieve is clogged: inspect the sieve and clean it.
The pipe filter is clogged: Inspect and clean the pilot valve setting or the air charge pressure is not properly adjusted.
Outlet pressure is low
There are five main reasons why your supply pressure is low, causing your pressure reducing valve to fail:
The setting of the pilot valve is not properly adjusted: modify it to the desired pressure.
The valve is undersized: check the actual load against the nominal capacity of the valve to determine if this is the cause.
The steam supply pressure is too low: Check the steam supply pressure and correct it.
The diaphragm of the main valve is broken: unscrew the copper tube connection and break the bypass valve. If steam comes out of the membrane box, the membrane is defective and must be replaced.
The purge hole is missing: replace the appropriate fitting.
Pressure reducing valve fails to close
There are five main reasons why the valve does not close, causing the failure of its pressure reducing valve:
The bypass valve is open or leaking: check and repair it if necessary.
The pilot detection line is blocked (or not installed): remove, inspect, clean or install.
The pilot has broken, which means that water or steam is coming out of the pilot seal area of the spring: replace the pilot diaphragm assembly.
The pilot assembly or the threads of the main valve seat are leaking: check the casting in the seat area for erosion.
The main valve diaphragm was reassembled without the return spring and main valve cover keeping the valve head closed: with the main valve cap installed, loosen all the main valve diaphragm bolts and then tighten them again.
In Valfonta, we are a family business with more than 50 years of experience in the manufacture of valves. All our products have the seal of guarantee of a brand with extensive experience in the sector. Therefore, if you have any questions about our valves, or if you need custom valves, contact us, and we will get to work immediately for you.
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