The illustrated device is in operation when...

🔍 Key Concepts

• Follow the flow arrows at points B and G to determine which way the liquid can move through the check valves. • Compare the shape of the device to a typical double-diaphragm pump vs a pneumatic feedback controller – look for diaphragms, check valves, and liquid chambers. • Remember that suction occurs where fluid is drawn into the pump chamber and discharge occurs where fluid is forced out through a one-way valve.

💭 Think About

• Look closely at the arrow symbols at B and G: do they show fluid entering the device or leaving it during operation? • When the diaphragms marked near A and E move outward, where would low pressure be created, and which check valve (B or G) would open as a result? • Does the internal layout (C, D, F) look more like a control relay with feedback lines, or like a pump with inlet and outlet check valves?

✅ Before You Answer

• Verify which side’s check valve symbol at B or G is oriented to allow flow into the chamber (this must be the suction side). • Verify which side’s check valve allows flow out of the chamber only (this must be the discharge side). • Confirm for yourself whether any parts are actually labeled or drawn like a pressure differential relay or force-balance relay before choosing options A or B.

The illustrated device is in operation when __________. See illustration GS-0061.

the output at "B" is providing negative feedback of the manipulated variable to the pressure differential relay

the output at "B" is providing positive feedback of the manipulated variable to the force balance relay

suction of the transferred liquid occurs at "G" and discharge at "B"

suction of the transferred liquid occurs at "B" and discharge at "G"

🔍 Key Concepts

💭 Think About

✅ Before You Answer