FIG. 104. VACOMETER FOR USE IN TESTING VACUUM CLEANING SYSTEMS.
A convenient form of testing appliance based on the orifice test is the vacometer, manufactured by the Spencer Turbine Cleaner Company and shown in [Fig. 104]. This device consists of a spherical aluminum casting, with a 1-in. diameter hole on the equatorial circle, a vacuum gauge being attached to one polar extremity, the other being attached to the end of the hose. A ring having a slip fit is placed around the equatorial circle in which openings varying from ¹⁄₂-in. to ⁷⁄₈-in. diameter are drilled. By turning this ring any of the orifices may be made to register with the opening in the sphere. The opening to which the vacuum gauge is attached is so located that it is not affected by the entering air current, and its readings are not affected by the velocity head.
Experiments with this instrument in connection with a Pitot tube show that a ¹⁄₂-in. diameter orifice is equivalent to a Type A carpet renovator, a ⁵⁄₈-in. orifice to a Type F renovator and a ⁷⁄₈-in. orifice to a bare floor renovator.
With instruments of this type equal in number to the capacity of the plant in sweepers, attached to the ends of the cleaning hose, it is possible to obtain uniform conditions equal to the average results that will be obtained in actual practice with renovators attached to the hose, without the possibility of expert manipulation of the renovators affecting the results.
The proper orifice to be used in each vacometer during the test will vary with the character of the service for which the plant is designed, and the author recommends the following for each of the classes of plants described in [Chapter XII]:
Class 1. 2-in. mercury, with ¹⁄₂-in. orifice, maximum length of hose to be used in actual cleaning.
Class 2. One-half the inlets ¹⁄₂-in. orifice, 4.5 in. mercury at one orifice attached at end of longest hose desired to use in practice, the remaining ¹⁄₂-in. outlets on shorter hose lengths. The other half of inlets to have ⁷⁄₈-in. orifices open at same time, with longest hose on one-quarter of total inlets and shortest on the balance.
Class 3. All inlets on long hose, one-half with ¹⁄₂-in. orifice, balance with ⁷⁄₈-in.
Class 4. All inlets to have ⁷⁄₈-in. orifice and 1 in. vacuum at vacometer, all hose lines maximum length.