Quick Connect Shut-Off Couplings

Koolance patent-pending quick disconnects (QDC) are specially designed fittings which automatically shut-off coolant flow upon disconnection. The flow path is reestablished when the couplings are connected. Quick disconnects are very useful for areas in a water cooling or plumbing system which are altered and moved frequently. They can also increase convenience when draining a system.

Koolance QDC Connected

QDC shutoffs work by having an internal valve which opens and closes as needed. Both male and female fittings contain a "plunger" that is spring-activated. When connected, the valves on both sides remain open to allow coolant to pass through. When disconnected, each side immediately self-seals. Koolance's current couplings are considered "no-spill" or "dry-break". This means very little coolant is freed upon disconnection. The insides of the fittings may be wet, but there is generally not enough liquid to form a drop on either side.

Koolance QDC Disconnected

Series and Sizes

Koolance offers three current series of quick connect couplings, which are intended for different tubing internal diameters. Each series is considerably larger in physical size than the previous:

NOTE: Different series are NOT physically compatible with one another. For example, a "QD2" fitting will not fit a "QD3" fitting.

Selecting Quick Disconnects


One female and one male fitting is required for any tube you wish to disconnect. To dry-break two hoses (inlet/outlet) going to a cold plate or pump, two male and two female couplings are needed. As long as Koolance fittings are selected from the same series, any male will connect with any female fitting.

Quick connect couplings can be placed "inline" (in the middle of tubing), or directly into a component like a cold plate or radiator. For direct connections, threaded QDC are used on the component side, with the opposite gendered coupling selected based on the hose size.

Koolance Threaded QDC

For example, you could select two QD3-MSG4 (male, threaded) fittings to be inserted into a CPU cold plate. On the tubing-side, you would need two QD3-Fxxx (where "xxx" matches your desired fitting style and hose size). Similarly, you could select QD3-FSG4 (female, threaded) for the component side, and QD3-Mxxx for the tubing side. It makes no difference which direction coolant flows through the quick connect couplings.

Koolance offers BKT-PCI-G for installations directly into a rear computer slot. This bracket has G 1/4 BSPP threads on both sides. Threaded quick connect couplings could be installed on the inside, outside, or both.

Identifying Earlier QDC Series

Koolance has produced several generations of quick connect couplings. These are mentioned in the below diagram.

Koolance QDC Series