12v DC 4mm 1/4" NPT Normally Closed Brass NBR 2-Way Solenoid Valve

A two way solenoid valve means that there are 2 ports in which fluid flows from/to. The Direct Acting valves will stop flow in either direction, but are still only designed to allow full flow in a single direction. Semi-Direct acting valves require assitance from fluid flow to open. These 2W valves may be used with 0 psi working pressure. However, while they do not require pressure from the working fluid to remain open or remain closed, these semi-direct lift valves do require some assistance from the flow of the working fluid for the initial opening/closing. Some gravity flow applications may have trouble overcoming the static friction of the seals within the valve while initially opening or closing and therefore the valve may not function properly in some low flow or low pressure applications.General purpose 2-way direct acting and semi-direct lift acting valves. Common applications include water, oil (below 20cst), air, gas, freon, *vacuum, weak acids & weak alkali. Check chemical compatibility charts for the valve body and seals of the valves to see if they are compatible in the case of using a weak acid/base. The Semi-Direct Lift valves will partially open or close from activation, and require fluid assitance to prop open or closed. They can only stop flow in one direction, which is indicated by the arrow on the body of the valve. If pressure is applied in the opposite direction, the valve will be opened and allow a slow trickle of fluid in the opposite direction. These valves should only be used for stopping flow in one direction. If preventing of backflow is required, a check valve should be placed in the line after the solenoid valve. Direct acting valves switch on their own with no fluid assitance and can block fluid flow in both directions.