01 Utilize Wide Openings:
Maximize control valve opening, aiming for around 90% initially. This minimizes air turbidity and erosion damage on the spool head.
As wear on the spool progresses over time, flow rates naturally increase, prompting a slight closure of the valve to maintain control. This gradual adjustment ensures the full utilization of the spool until wear renders the spool's root and sealing surface unusable.
Additionally, operating control valves at wider openings helps mitigate erosion in throttle clearances, ultimately extending the valve's lifespan by up to 1-5 times compared to operation at mid-range or small openings.
02 Minimize Valve Resistance Ratio:
Reducing the valve resistance (S) entails increasing system losses aside from the regulating valve. This redistributes pressure drop across the valve, decreasing flow through the regulator while inevitably enlarging its opening. Consequently, pressure drop on the valve decreases, mitigating cavitation and erosion.
Specific methods include installing an orifice plate downstream for throttling pressure drop or closing manual valves in series with the pipeline to achieve an ideal operating opening for the regulating valve. This method is straightforward, convenient, and highly effective, especially when selecting a valve with a small initial opening.
03 Optimize Valve Size and Opening:
Decreasing valve caliber increases working opening. Methods include switching to a smaller caliber valve (e.g., DN32 to DN25) or replacing the valve seat with a smaller diameter spool.
04 Relocate Damage Areas:
Shift severe damage from primary to secondary locations to safeguard the spool, seat sealing surface, and throttling surface, thus enhancing valve service life.
05 Alter Flow Direction:
Changing the flow direction can impact the longevity of the valve. Flowing open towards the spool's opening direction may lead to cavitation and erosion primarily on the sealing surface, resulting in early damage to the spool root and valve seat sealing surface. Conversely, flowing closed towards the closing direction directs cavitation and erosion below the throttling seat sealing surface, safeguarding the spool root and sealing surface, thereby extending valve life.
Note: Changing from flow open to flow closed may induce a jump phenomenon (valve opening), affecting the regulation process due to vortex influence. Careful and comprehensive consideration is necessary when employing this method.
06 Utilize Special Materials:
To combat cavitation (which creates honeycomb-shaped pitting) and scouring (resulting in streamlined deposits), consider utilizing special materials resistant to such effects for throttle parts. Examples include 6YC-1, A4 steel, Stellet, carbide, etc. Additionally, for corrosion resistance, opt for materials with superior resistance and suitable mechanical and physical properties. These materials can be non-metallic (e.g., rubber, PTFE, ceramics) or metallic (e.g., Monel, Hastelloy).
07 Select Appropriate Valve Structure:
Control valves offer several advantages during operation, including agile action, ability to handle larger moments with large cylinders, stable performance in harsh environments, and high safety performance. The smooth operation and agility of control valves directly impact production quality and efficiency. Therefore, it's crucial to analyze and implement measures to address factors influencing control valve failure during usage.
