1、 Positive acting pressure reducing valve

由于主閥彈簧須克服進(jìn)口介質(zhì)對(duì)閥瓣的作用力及提供的密封力，因此，主閥彈簧的負(fù)荷較大。不適用于大口徑的場合。壓力特性偏差和流量特性偏差都是“負(fù)”值。所以任一工況時(shí)的靜偏差都為“負(fù)”。同時(shí)，主閥彈簧的負(fù)荷較大，而它的結(jié)構(gòu)空間卻有限為了獲得大的負(fù)荷，只有提高剛度。因此，它的靜偏差較大。

Due to the fact that the main valve spring must overcome the force of the imported medium on the valve disc and the sealing force provided, the load on the main valve spring is relatively high. Not suitable for large caliber applications. The pressure characteristic deviation and flow characteristic deviation are both "negative" values. So the static deviation under any working condition is "negative". At the same time, the main valve spring has a large load, but its structural space is limited. In order to obtain a large load, the only way is to increase the stiffness. Therefore, its static deviation is relatively large.

由于上述原因，正作用式減壓閥通常只適用于小口徑（小于DN5以下）低流量的場合。

Due to the above reasons, positive acting pressure reducing valves are usually only suitable for small diameter (less than DN5) and low flow situations.

二、反作用式減壓閥

2、 Reaction type pressure reducing valve

進(jìn)口介質(zhì)使閥瓣壓向閥座，保證了閥的密封。主閥彈簧只需承受運(yùn)動(dòng)部件的重力，負(fù)荷較小。因此有較小的流量特性偏差。W=0時(shí)，在進(jìn)口壓力降低到與出口壓力相等之前，壓力特性偏差是逐漸正向增加的。W≠0時(shí)，在進(jìn)口壓力降到與出口壓力相等之前，壓力特性偏差就由增加轉(zhuǎn)為下降，直至變?yōu)樨?fù)偏差。W越大，開始轉(zhuǎn)為下降特性的進(jìn)口壓力也越高。

The imported medium presses the valve disc against the valve seat, ensuring the sealing of the valve. The main valve spring only needs to bear the weight of the moving parts and has a small load. Therefore, there is a small deviation in flow characteristics. When W=0, the pressure characteristic deviation gradually increases positively before the inlet pressure decreases to the same level as the outlet pressure. When W ≠ 0, the pressure characteristic deviation changes from increasing to decreasing until it becomes negative before the inlet pressure drops to the same level as the outlet pressure. The larger the W, the higher the inlet pressure at which the descent characteristic begins.

反作用式減壓閥通常都具有“正”向的靜偏差。只有當(dāng)流量很大，而進(jìn)口壓力接近大或小值時(shí)，靜偏差才為“負(fù)”。所以，當(dāng)需要獲得“正”向偏差時(shí)，以采用反作用式減壓閥為宜。

Reaction type pressure reducing valves usually have a "positive" static deviation. Only when the flow rate is high and the inlet pressure is close to the high or low value, the static deviation is "negative". Therefore, when it is necessary to obtain a "positive" deviation, it is advisable to use a reaction type pressure reducing valve.

由于需要從閥座中穿過，故不宜于小口徑的場合。同時(shí)，由于調(diào)節(jié)彈簧須克服進(jìn)口介質(zhì)對(duì)閥瓣的作用力，所以，當(dāng)進(jìn)口壓力較高，而口徑很大時(shí)，調(diào)節(jié)彈簧必須承受的負(fù)荷極大?？赡茉斐烧{(diào)節(jié)彈簧極不合理的設(shè)計(jì)。

Due to the need to pass through the valve seat, it is not suitable for small caliber applications. At the same time, due to the fact that the adjusting spring must overcome the force of the inlet medium on the valve disc, when the inlet pressure is high and the diameter is large, the adjusting spring must bear a great load. May cause extremely unreasonable design of the adjustment spring.

另外，閥座密封面所承受的力也相當(dāng)大。所以反作用式減壓閥通常適用于進(jìn)口壓力（嚴(yán)格地說應(yīng)指進(jìn)、出口壓力差）不太高，中等口徑的場合。當(dāng)進(jìn)口壓力較高時(shí)，口徑必須較小，而進(jìn)口壓力較低時(shí)，口徑允許較大。主要取決于是否獲得尺寸合理的調(diào)節(jié)彈簧及閥座密封副能否承受進(jìn)口介質(zhì)的作用力。

In addition, the force on the sealing surface of the valve seat is also considerable. So reaction type pressure reducing valves are usually suitable for situations where the inlet pressure (strictly speaking, the pressure difference between the inlet and outlet) is not too high and the diameter is medium. When the inlet pressure is high, the diameter must be smaller, while when the inlet pressure is low, the diameter is allowed to be larger. It mainly depends on whether a reasonably sized adjusting spring and valve seat sealing pair can withstand the force of imported media.

三、卸荷式減壓閥

3、 Unloading pressure reducing valve

卸荷式是靜態(tài)性能較為理想的形式。由于pj不參加運(yùn)動(dòng)部件的力平衡，壓力特性偏差極小。W=0時(shí)，壓力特性偏差為零。W≠0時(shí)，壓力特性偏差為“負(fù)”，所以靜偏差恒為“負(fù)”值。閥彈簧僅需提供密封力和克服運(yùn)動(dòng)部件的重力。

Unloading type is an ideal form of static performance. Due to Pj not participating in the force balance of moving components, the deviation of pressure characteristics is minimal. When W=0, the pressure characteristic deviation is zero. When W ≠ 0, the pressure characteristic deviation is "negative", so the static deviation is always a "negative" value. The valve spring only needs to provide sealing force and overcome the gravity of moving parts.

調(diào)節(jié)彈簧無須克服介質(zhì)對(duì)閥瓣的作用力。所以，閥彈簧和調(diào)節(jié)彈簧都只承受較小的負(fù)荷，從而剛度也可設(shè)計(jì)得較小。所以，靜偏差較上述兩種形式小。除了由于閥桿必須從閥座中穿過而不適用小口徑的情況外，其適用范圍較大。

Adjusting the spring does not require overcoming the force of the medium on the valve disc. So, both the valve spring and the adjustment spring can only withstand small loads, so the stiffness can also be designed to be smaller. Therefore, the static deviation is smaller than the above two forms. Except for situations where the valve stem must pass through the valve seat and is not suitable for small diameters, its applicability is relatively large.

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