Balance of the pneumatic valve design and type selection

balanced pneumatic valve is commonly used in air conditioning system of a pneumatic valve, generally can be divided into two types of manual and automatic control, its right selection, is directly related to the normal running of the whole control system, the following we by manual and automatic two kinds of structure to talk about their principle and selection, respectively. A pneumatic valve, manual balance

. Manual balance the working principle of pneumatic valve
manual balanced pneumatic valve is one-time manual regulation, can not automatically changes over system working condition of drag coefficient, so that the static balance pneumatic valve. Manual balance is the object of the pneumatic valve role resistance, can have the effect of manually adjustable orifice, the resistance of pipeline system is to balance, reach the role of each loop resistance balance. Can solve the problem of steady state misadjustment of system: when the operation condition is different from design conditions, circulating water is more than or less than the design conditions, as a result of the balancing pneumatic valve is system resistance, to the distribution of the new water proportion according to the design and calculation of balance, make the flow of the slip road will be in proportion to increase or decrease at the same time, still meet the requirement that corresponds to the current load flow
. Manual selection of the balance of the pneumatic valve and problems should be paid attention to in the design of the
( Pneumatic valve characteristic curve determines the regulation performance of the pneumatic valve, such as by pneumatic valve flow curve, if think traffic between % ~ % change is meaningless, so opening from ~ % is realized in the whole process of the flow changes, such as pneumatic valves cannot be used as the working condition of hydraulic balance regulation. Due to the theory of pneumatic valve characteristic curve was measured under the roof pressure difference, and the the actual working condition as long as the right of the pneumatic valve for pneumatic valve, pneumatic valve in the small open line before and after the pressure difference is big, big pressure difference before and after pneumatic valve opening is small, lead to dG/dC values in a small open of the pneumatic valve, when the big opening smaller, pneumatic valve working curve drift in the direction of quick opening, the right of the pneumatic valve, the smaller the deviation, the greater the for linear characteristics of pneumatic valves due to the actual performance of the offset of pneumatic valves regulate the open degree of space smaller, so the pneumatic valve theoretical curve for percentage of properties such as lower chord arc as well. Percentage of characteristic curve of pneumatic valve, in the right of the pneumatic valve. ~。 When the working curve could be close to linear features.
( Usually pneumatic valve under the condition of small open degree of pneumatic valve flow rate is too high, after pneumatic valve can form strong turbulent vortex zone, vortex area and the new pressure is low, it is lower than the temperature corresponding to the saturation pressure of water vapor pressure flash play in soda strike phenomenon: serious noise, the vibration of the pneumatic valve and pipe, pneumatic valves, pipes, pipe support. Prevention and control of such accidents in the first place in the pneumatic valve pneumatic valve plug flow design considerations and pneumatic seat formed when narrow throttling channel in a small open degree, restriction of strong turbulent vortex formation; Second when choosing pneumatic valve to increase the rights of the pneumatic valve as far as possible, to avoid the pneumatic valve under the small open degree of operation. In addition, in as far as possible when not working pressure involved alkali balance of pneumatic valve installed in the low temperature return pipe.
2, self-reliance balance type pneumatic valve
. Self-reliance type balance working principle of the pneumatic valve
self balance type pneumatic valve can be in the absence of an external power supply, automatic flow balance of the system. Balance of self-reliance type pneumatic valve is through keep orifice ( Fixed aperture) Qualified traffic pressure difference before and after a while, therefore, can also be called constant flow pneumatic valve.
object is a certain flow pneumatic valve flow, can lock the water through the pneumatic valve, rather than the balance of the resistance. He was able to solve the problem of system dynamic disorder: in order to maintain a single chiller, boiler, cooling tower, heat exchanger efficiency of the equipment, is the need to control the equipment flow fixed in rating; From the end of the system, in order to avoid dynamic adjustment influence each other, also need to be in the end of the device or the branch flow restrictions. Problems should be paid attention to in the design of the

self-reliance type flow control pneumatic valve faults is pneumatic valves have minimum differential work demand, the common product requirement minimum working pressure differential KPa, if installed in the most unfavorable way back, certainly will require the work head of water circulating pump more to increase meters, so should be taken to the proximal installation, remote method. When users away from the heat source distance is greater than the % of heating radius, do not have to install this type pneumatic valve flow control themselves.