1640系列 用于三位控制的微差壓開關是在1630系列開關的基礎上創新出來的微差壓開關，它帶有一個單刀雙擲的浮動觸點開關，能保持開關在一個中間位置。
示意圖展示了工作原理：當隔膜被差壓推動，它帶動浮點開關在兩個預設點產生動作，如果在預設點之間，開關沒有任何動作。當差壓升高到高預設點時，高位開關關閉，當差壓降低到低預設點時，低位開關關閉。
典型的應用例子為馬達驅動的風門，當風管中的靜壓增大到zui大預設點時，開關會控制驅動風門位置變化，當靜壓降低到zui小預設點時，開關也會驅動風門位置表話。如果采用皮托管配合使用，是一樣的道理來控制風速，是供風管保持恒量供風。
注意：只能用于空氣或其它兼容性氣體。
Service: Air and non-combustible, compatible gases.
Wetted Materials: Consult factory.
Temperature Limits: -30 to 110°F (-34.4 to 43.3°C).
Pressure Limits: 10 psig (68.95 kPa) continuous, 25 psig (172.4 kPa) surge.
Switch Type: Single-pole double throw (SPDT) floating contact (not snap action).
Electrical Rating: Non-inductive: 2.5 A @ 110 VAC, 1.5 A @ 220 VAC, 1 A @ 24 VDC, 0.5 A @ 110 VAC; Inductive: 1 A @ 110 VAC, 0.5 A @ 220 VAC, 0.5 A @ 24 VDC. (De-rate 70-80% for very slow pressure changes.)
Electrical Connections: 3 screw type, common, normally open and normally closed.
Process Connections: 1/8" female NPT.
Mounting Orientation: Diaphragm in vertical position. Consult factory for other position orientations.
Set Point Adjustment: Screw type.
Weight: 4 lb 13 oz (2.18 kg).
Agency Approvals: CE.
