Factors Affecting the Stable Operation of Gas Pressure Regulating Valves
1. Working Principle of Domestic Pressure Reducing Valves
The pilot valve is adjusted by rotating the adjusting bolt at the top clockwise, which compresses the spring and causes the diaphragm to sag downward. This movement shifts the force on the connecting rod, allowing the guide valve to open. When the pilot valve opens, steam from the upstream pipe section a flows through the α channel (supply steam regulating passage), enters the annular steam chamber of the pilot valve, and is directed to the upper chamber of the piston cylinder via the β channel. As steam continuously fills this chamber, pressure increases, pushing the piston down and opening the main valve. Steam then flows from cavity a to cavity b. When the downstream load in cavity b is satisfied, excess steam causes pressure to rise. This increased pressure is fed back to the lower chamber of the pilot diaphragm through the γ channel (pressure sensing channel), causing the diaphragm to bulge upward, overcoming the spring force and closing the pilot valve. This stops the steam supply from cavity a. As pressure in the piston’s upper chamber drops, the return spring closes the main valve. The pressure in cavity b then decreases, restarting the regulation cycle.
2. Working Principle of Imported Pressure Reducing Valves
When the pilot valve opens, steam from the upstream pipe section a quickly enters the inner filter cover and flows through the pilot valve into the a channel (supply steam regulating passage). Once filled, steam is sent to the lower diaphragm of the main valve, while part of it flows into the b chamber via the b channel (pressure control channel). The continuous steam supply to the lower chamber of the main valve diaphragm pushes it upward, generating enough force to lift the main valve rod and open the main valve. Steam then flows from a to b. When the downstream load is met, excess steam raises the pressure in cavity b, which is transmitted to the lower steam chamber of the pilot diaphragm via the c channel (pressure sensing channel). This causes the pilot diaphragm to rise, closing the pilot valve and cutting off the steam supply from cavity a. As pressure in the main valve diaphragm’s lower chamber decreases, the return spring lowers the main valve spool, closing the valve. Excess steam is released through the b channel, and the main valve shuts quickly, reducing pressure in cavity b and completing the adjustment.
3. Analysis of Condensate Water Damage Mechanism
When the downstream pressure in cavity b rises and needs to be reduced, the high pressure is typically transmitted through the γ channel to the pilot valve, causing it to close and cut off the steam source from cavity a. However, if condensate water enters the cylinder or the annular steam chamber, the incompressible nature of water prevents the main valve return spring from functioning properly. This means the piston cannot move up, and the main valve remains open, allowing continuous steam flow from a to b, leading to uncontrolled pressure. If condensate fills both a and b channels and the lower chamber of the main diaphragm, the steam pressure from cavity a pushes the diaphragm upward. Since water is incompressible, the return spring cannot push the diaphragm back, keeping the main valve in an open state and destroying the regulation function.
Although pressure reducing valves are designed as proportional control devices, when condensate water fills their critical working parts, their proportional adjustment capability is completely compromised. Key issues include the frictional resistance of moving components and the sequence of actions. The time delay between the pilot valve and the main valve leads to hysteresis in the main valve’s motion. After receiving an overpressure signal from the γ or c channels, the pilot valve acts first, followed by the main valve. This delay can trap condensate inside the valve, preventing the piston and diaphragm from moving.
In conclusion, system condensate is highly detrimental to heating projects. It is the primary cause of failure in the regulation function of steam pressure reducing valves.
(Source: Hebei Zhenxing Gas Pressure Regulator Co., Ltd.)
Http://news.chinawj.com.cn Editor: Hardware Business Network Information Center http://news.chinawj.com.cn
1. Working Principle of Domestic Pressure Reducing Valves
The pilot valve is adjusted by rotating the adjusting bolt at the top clockwise, which compresses the spring and causes the diaphragm to sag downward. This movement shifts the force on the connecting rod, allowing the guide valve to open. When the pilot valve opens, steam from the upstream pipe section a flows through the α channel (supply steam regulating passage), enters the annular steam chamber of the pilot valve, and is directed to the upper chamber of the piston cylinder via the β channel. As steam continuously fills this chamber, pressure increases, pushing the piston down and opening the main valve. Steam then flows from cavity a to cavity b. When the downstream load in cavity b is satisfied, excess steam causes pressure to rise. This increased pressure is fed back to the lower chamber of the pilot diaphragm through the γ channel (pressure sensing channel), causing the diaphragm to bulge upward, overcoming the spring force and closing the pilot valve. This stops the steam supply from cavity a. As pressure in the piston’s upper chamber drops, the return spring closes the main valve. The pressure in cavity b then decreases, restarting the regulation cycle.
2. Working Principle of Imported Pressure Reducing Valves
When the pilot valve opens, steam from the upstream pipe section a quickly enters the inner filter cover and flows through the pilot valve into the a channel (supply steam regulating passage). Once filled, steam is sent to the lower diaphragm of the main valve, while part of it flows into the b chamber via the b channel (pressure control channel). The continuous steam supply to the lower chamber of the main valve diaphragm pushes it upward, generating enough force to lift the main valve rod and open the main valve. Steam then flows from a to b. When the downstream load is met, excess steam raises the pressure in cavity b, which is transmitted to the lower steam chamber of the pilot diaphragm via the c channel (pressure sensing channel). This causes the pilot diaphragm to rise, closing the pilot valve and cutting off the steam supply from cavity a. As pressure in the main valve diaphragm’s lower chamber decreases, the return spring lowers the main valve spool, closing the valve. Excess steam is released through the b channel, and the main valve shuts quickly, reducing pressure in cavity b and completing the adjustment.
3. Analysis of Condensate Water Damage Mechanism
When the downstream pressure in cavity b rises and needs to be reduced, the high pressure is typically transmitted through the γ channel to the pilot valve, causing it to close and cut off the steam source from cavity a. However, if condensate water enters the cylinder or the annular steam chamber, the incompressible nature of water prevents the main valve return spring from functioning properly. This means the piston cannot move up, and the main valve remains open, allowing continuous steam flow from a to b, leading to uncontrolled pressure. If condensate fills both a and b channels and the lower chamber of the main diaphragm, the steam pressure from cavity a pushes the diaphragm upward. Since water is incompressible, the return spring cannot push the diaphragm back, keeping the main valve in an open state and destroying the regulation function.
Although pressure reducing valves are designed as proportional control devices, when condensate water fills their critical working parts, their proportional adjustment capability is completely compromised. Key issues include the frictional resistance of moving components and the sequence of actions. The time delay between the pilot valve and the main valve leads to hysteresis in the main valve’s motion. After receiving an overpressure signal from the γ or c channels, the pilot valve acts first, followed by the main valve. This delay can trap condensate inside the valve, preventing the piston and diaphragm from moving.
In conclusion, system condensate is highly detrimental to heating projects. It is the primary cause of failure in the regulation function of steam pressure reducing valves.
(Source: Hebei Zhenxing Gas Pressure Regulator Co., Ltd.)
Http://news.chinawj.com.cn Editor: Hardware Business Network Information Center http://news.chinawj.com.cn
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