States of dynamic equilibrium of gas flows and absolute pressures in vacuum chambers are used in some methods of pressure unit realization in the range of low absolute pressure (high vacuum) to reduce (or divide) the initial relatively high pressure. Some of them are the continuous expansion (orifice flow) method and the static expansion method. For the basic methods of the flow unit realization (Pa.m3s-1), such as the method of constant pressure and the method of constant volume, the exact measurements of absolute pressure is necessary. These two physical quantities depend on each other in accordance with the flow definition and the methods of pressure unite realization. Some possibilities of employment of such pressure reference standards as piston gauge, manometer of McLeod, U-tube manometer to measure of rarefied gas pressure and flow are noted. Advantages of this “mutual cooperation” are shown. A development of a reference standard for realization of these two principal physical quantities of vacuum technique on the unique methodological and instrumental base is discussed. In present work a design of combined vacuum reference standard to be developed in accordance with the project PADRAVAC is proposed. This project was approved by the National Science Research Committee of Brazil (CNPq). A combination of static expansion method and classic two-orifice continuous expansion method is offered to be used for realization of low absolute pressure unit in the range (103 – 10-5) Pa. The method of constant volume and the method of orifice flow (with long glass cylindrical capillaries) are proposed to be employed for realization of flow (throughput) unit in the range (1-10-8) Pa.m3s-1 at the same apparatus. Interaction of mentioned methods under the realization of pressure and flow units is described. Calculations of range limits and expanded errors of every method have been carried out.
