1, Boyle's law

 Volume V, pressure strength P, P · V= constant

A certain mass of gas, when the temperature is constant, the pressure of the gas is inversely proportional to the volume of the gas.

approach P₁/P₂＝V₂/V₁

2. Guy Lusac's Law

When the pressure P is constant, the volume V of a gas of a certain mass is proportional to the * temperature of T:

 V₁/V₂＝T₁/T₂= constant

When the pressure is unchanged, the temperature of a certain mass of gas increases 1℃ (or P decreases), then its volume increases (or decreases 1 /) 273.

3. Charlie's Law

When the volume V of the gas remains unchanged, the pressure P is proportional to the temperature T, namely:

 P₁/P₂＝T₁/T₂

In a certain volume, a certain mass of gas, each temperature increases (or decreases) 1℃, its pressure increases (or decreases) 1 / 273.

4. Average free path: λ = (510^-3)/P (cm)

5. Draw speed: S=d_v/d_t(L / sec) or S=Q / P

Q= Flow (lift · l / s) P= Pressure (lift) V= volume (l) t= time (seconds)

6. Guide: C=Q / (P₂-P₁) (L / s)

7. Vacuum extraction time: for the extraction time from atmospheric pressure to 1 pressure:

t=8V / S (empirical formula)

V is the volume and S is the pumping rate, and t is usually chosen within 5 to 10 min.

8. Maintenance pump selection: S_{tie up}＝S_front/10

9. Estimation of the diffusion pump pumping rate: S=3D²(D= diameter cm)

10. Front pumping speed of Roots pump: S= (0.1~0.2) S_{a net for catching birds}(l/s)

11. Leak rate: Q_leak＝V(P₂-P₁)/(t₂-t₁)

Q_leak-System leakage rate (mmHg · l / s)

V-System Volume (l)

P₁-System medium pressure (mmHg) at vacuum pump stops

P₂-Pressure achieved in the vacuum chamber after time t (mmHg)

The t-pressure from P₁Up to P₂Exapsed Time (s)

12. Selection of crude pump pumping speed: S=Q₁/P_{in advance}(l/s)     S=2.3V·lg(P_a/P_{in advance})/t

S-Effective pumping rate of the mechanical pump

Q₁-Air leakage rate of vacuum system (liter / s)

P_{in advance}-Pre-vacuum to be achieved (support)

V-Vacuum system volume (L)

t-achieve P_{in advance}The time required

P_a-Atmospheric pressure value (support)

13. Front-stage pump pumping speed selection:

The transmission pump with exhaust port pressure lower than one atmospheric pressure, such as diffusion pump, oil booster pump, Roots pump, turbine molecular pump, etc., requires the front pump to maintain its front pressure below the critical value. The selected front pump must be able to discharge the * * gas volume of the main pump. According to the pipeline, the constant flow principle of each section is as follows:

P_nS_g≥P_gS perhaps

S_g≥P_gs/P_n

S_g-Effective pumping rate of the front-stage pump (l / s)

P_n-Main pump critical front pressure (* * exhaust pressure) (l / s)

P_g-Vacuum chamber * high working pressure (support)

The S-Main pump is working at the P_gEffective pumping speed at.(l/s)

14. Calculation formula of diffusion pump pumping speed: S=Q / P= (K · n) / (P · t) (l / s)

Where: S-The extraction rate of the tested pump (l / s)

N-Upgrade on the oil column (grid)

Time (seconds)

P-Pressure measured near pump port (support)

K-Dropper coefficient (· l / s)

K＝V₀·(L/n)·(Υ₀/Υ_m)+P_a△V_t

among V₀-Original volume of dropper and vacuum hose (l)

L-Length of the dropper scale section (mm)

Number of cells of the n-dropper scale part (cells)

Υ₀-Specific gravity of the oil (g / cm³)

Υ_m-The specific gravity of mercury (g / cm³)

P_a-Local atmospheric pressure (support)

△V_t-Corresponding volume on the scale of the dropper (l / case)

15. The geometric extraction speed calculation formula of rotary wafer vacuum pump: S= π ZnLK_v(D²-d²)/(24×10⁴) (l/s)

Where Z is the number of wafers, n is the speed (rpm), L is the pump chamber length, D is the pump chamber diameter, d is the rotor diameter (cm), K_vIs the volume utilization coefficient (generally take 95%).

16, O-type rubber groove depth of B=0.7D

D is the rubber diameter, groove width C=1.6B

17, square rubber groove depth of B=0.8A

A is the square rubber side length, and the groove width is C=1.67B