An isolation transformer is a type of transformer with symmetrical winding, which is mainly used to decouple two electric circuits. It allows an AC signal or power to be taken from one device and fed into another without electrically connecting the two circuits It blocks transmission of DC signals from one circuit to the other, but allow AC signals to pass. They also block interference caused by ground loops. Isolation transformers with electrostatic shields are used for power supplies for sensitive equipment such as computers or laboratory instruments. Isolation transformers are commonly designed with careful attention to capacitive coupling between the two windings. This is necessary because excessive capacitance could also couple AC current from the primary to the secondary. A grounded shield is commonly interposed between the primary and the secondary. Any remaining capacitive coupling between the secondary and ground simply causes the secondary to become balanced about the ground potential.
An isolation valve is a valve designed to separate or isolate the fluid media from the inner workings of the valve. These are used for diverting process media, facilitating maintenance, equipment removal and shutdown. In a solenoid valve this is typically accomplished using a diaphragm. Also known as a diaphragm valve, the only materials wetted by the fluid media are the valve body and the diaphragm itself. The plunger and spring are isolated from the fluid media. Isolation valves are typically desirable in sensitive applications such as scientific and medical instrumentation, where engineers want to maintain the chemical integrity of a fluid sample.