A pressure brake bleeder is a tool that enables brakes to be bled quickly and easily. It is the tool of choice for this purpose in professional workshops yet need be no more expensive than a vacuum brake bleeder (one problem of which is it tends to pull in air from around the bleed fitting). Basically, a pressure bleeder consists of a storage tank with two reservoirs separated by a diaphragm. The lower reservoir is filled with enough brake fluid to completely flush the system, while the upper part is pressurized to about 15 psi (as metered by a gauge attached to the bleeder). The brake fluid reservoir is connected by a hose to an adaptor on the master cylinder. A valve in the hose is opened slowly causing old or contaminated fluid to be forced out while, at the same time, new fluid from the pressure tank is added.