美国仙童FAIRCHILD，21型可调比率继电器
Model 21 Adjustable Ratio RelayPart Number: M21
Model 21 Adjustable Ratio pneumatic relay has a signal chamber lever arm, whereby the ratio of output pressure to signal pressure is infinitely adjustable. The adjustment range permits signal amplification of 1:30 or signal reduction of 30:1 by rotation of the ratio adjustment knob which moves the fulcrum. . Output pressure is a function of signal pressure times the ratio of lever arm lengths on either side of the fulcrum. Bias may be introduced by means of the set screws. The Model 21D is available with both input and output adjustable bias. Maximum input bias is 3 psig, with a maximum output bias of 9 psig. The basic mathematical expression for the bias in this relay is Po = (Ps-K1) R+K2, where Po = Output pressure, Ps = Input signal, R = Ratio of setting, K1= Input bias, (-) only, and K2 = Output bias, (+) only.Features
Adjustable from 30:1 dividing ratio to 1:30 multiplying ratio
Venturi aspiration system
Optional input and output biasing
Floating seal ring isolates control chamber
Panel or line mounting
Benefits
Assures infinite pressure adjustments
Compensates for downstream pressure losses
Allows versatility in applications
Increased stability by reducing effect of high flows
Easy installation and service in the field
型号21可调比率继电器部件编号:M21
21型可调比气动继电器具有信号室杠杆臂，输出压力与信号压力之比可无限调节。调节范围允许信号放大1:30或信号减少30:1通过旋转比例调节旋钮移动支点。输出压力是信号压力乘以支点两侧杠杆臂长度之比的函数。固定螺钉可能会引起偏置。型号21D可提供输入和输出可调偏置。最大输入偏置为3 psig，最大输出偏置为9 psig。该继电器偏置的基本数学表达式为Po = (Ps-K1) R+K2，其中Po =输出压力，Ps =输入信号，R =整定比，K1=输入偏置，仅(-)，K2 =输出偏置，仅(+)。特性
从30:1分割比到1:30倍增比可调
文丘里吸气系统
可选的输入和输出偏置
浮动密封圈隔离控制室
面板或线路安装
好处
确保无限压力调节
补偿下游压力损失
允许应用程序的多功能性
通过减少高流量的影响来增加稳定性
易于现场安装和维修
