METHOD TO TEST PRODUCT FOR TIGHTNESS Russian patent published in 2014 - IPC G01M3/00 

FIELD: testing equipment.

SUBSTANCE: invention relates to the field of machine building, in particular, to testing equipment, and makes it possible to perform a full complex of product testing for tightness. The method is proposed to test the product for tightness, which consists in the fact that the product 6 is placed into a tight test chamber 1, equipped with systems of cooling 3 and heating 4. After vacuumising of the product 6 cavity, a control medium is sent in it, by increasing temperature they bring the control medium into the state of the supercritical fluid, then they perform operations of registration and measurement of the flow of the control medium penetrating in through microleaks of the product. The control medium in the form of a gas phase of liquefied gas or in the form of a liquid is supplied into the cavity of the product for testing in the amount $$M_o=V\cdot {\rho }_{cr}\cdot \frac{{Р}_{fl}}{{Р}_{cr}}\cdot \frac{{Т}_{cr}}{{Т}_{fl}},kg,$$ where V - volume of the product cavity, l; ρ_cr - critical density of the control medium substance, kg/l; P_fl - required pressure of the supercritical fluid in the product cavity during tests in the range of values P_cr≤P_fl≤3P_cr, kgf/cm²; P_cr - critical pressure of the control medium substance, kgf/cm²; T_cr - absolute value of critical temperature of the control medium substance, K; T_fl - absolute temperature of the supercritical fluid in the cavity of the product when testing in the range of values T_cr≤T_fl≤2T_cr, K. Supply of the gas phase of the liquefied gas with total amount M_o is carried out into the cavity of the product 6, previously cooled down to the temperature with the operating system of heat removal, at the same time the flow rate of the supplied gas: $$G\le \frac{N_Q}{r+C_{lq}\left(t_o-t_u\right)},kg/s,$$ where N_Q - thermal capacity of the system of heat removal from the surface of the product, kJ/s; t_u - temperature of the product during filling of the cavity with gas, °C; t_cm - temperature of hardening of the control medium in the liquid phase; C_lq - heat capacity of the condensed control medium at temperature $$t=\frac{t_o+t_u}{2},$$ kJ/kg·degrees; r - heat of condensation of the gas phase of the control medium at temperature $$t=\frac{t_o+t_u}{2},$$ kJ/kg; t_o - temperature of environment during the test,°C.

EFFECT: invention expands process capabilities of a test due to usage of different control gas and liquid media, and also to increase sensitivity and reliability of control of products with especially high requirements for tightness.

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