This McLeod vacuum gauge is a tilting gauge with a constant zero overflow which eliminates the capillary-depression error from an expanding meniscus

The McLeod gauge is useful for measuring pressures of true gases only. Water vapors and other condensable vapors should not be permitted to enter the gauge, since they can cause erroneous readings. The metal locking device has positive holding action—which eliminates need for glass hooks and springs.

This gauge will hold at any operating position to which it is rotated. A tapped hole is provided in the rear of the stand to accommodate the 6" threaded mounting rod for frame mounting (optional). The joint is [ST] 20/65. This gauge requires approximately 20mL of mercury, which is not supplied. Gauges are fabricated from calibrated ACE Trubore® glass tubing to assure a uniform and reproducible reading between the gauges. This feature is also important when broken scales must be replaced, since it enables us to supply new scales without re-calibrating the instrument.

Once the zero line of the scale is aligned with the tip of the closed capillary, it is only necessary to bring the gauge to an upright position and read the scale behind the closed leg. Mercury overflows to maintain a constant head. Bulbs are enlarged for easier pumping—longer mercury flow. The mercury trap is incorporated into the female joint instead of the gauge, which allows unobstructed access in cleaning.