Vacuum system leak detection

Vacuum system leak detection

According to ISO3529/1 definition, vacuum refers to a diluted gas or related state gas whose gas pressure or concentration is lower than the surrounding atmospheric pressure. In the SI International System of Units, the pressure unit is Pascal (Pa). In vacuum technology pressure is usually referred to as absolute pressure.
1Pa =1N/m2

A pressure of 1Pa is equal to a force of 1 Newton applied to a flat surface of 1 square meter.

Standard atmospheric pressure: the temperature is 0 ℃, the atmospheric pressure at sea level is called the standard atmospheric pressure, and the value is 101325Pa.

Obviously, the value of Pa is relatively small, so there are many practical units in practical engineering applications. See conversion below.

In some application fields, such as medical vacuum suction, vacuum suction cups, etc., when the absolute pressure is higher than 100Pa, there is still the concept of using negative pressure and vacuum degree (relative vacuum).

The concept of negative pressure is to take the standard atmospheric pressure of sea level as "zero", and the absolute vacuum is minus 1 atmosphere of pressure.

Relative vacuum, expressed by vacuum degree: (Pn-P) / P *100%.

When the pressure is Pn, the standard atmospheric pressure, the vacuum degree is 0%, and when the absolute vacuum is P=0, the vacuum degree is 100%.

In the field of practical vacuum application and vacuum technology research, the currently available and applied pressure range is: 105-10-10 Pa.

Spans 15 orders of magnitude. In order to facilitate technical communication and according to the characteristics in different pressure ranges, it is usually divided into four vacuum regions.
Vacuum area Rough vacuum Low vacuum Medium vacuum High vacuum Ultra high vacuum
Pressure range 105-103 103-101 101-10-2 10-2-10-6 10-6-10-10
Key features Differential pressure Oxygen and water content
Significant reduction
Substance boiling point decreases
Further reduction in oxygen content
The mean free path of gas molecules increases The time to form a monolayer increases
Main application Vacuum conveying
Vacuum Fixtures
Vacuum packing
Vacuum drying
Vacuum freeze drying
Vacuum distillation
Vacuum heat treatment
Electronic engineering
Mass spectrometer
Surface science
Space simulation
Get device Liquid ring vacuum pump
Single stage rotary vane vacuum pump
Single stage rotary vane vacuum pump Two-stage rotary vane vacuum
Roots vacuum pump
Diffusion pump
Molecular pump
Ion pump
Titanium Sublimation pump
Measurement method Analog vacuum gauge (boulton gauge) Resistance vacuum gauge
Boulton vacuum gauge
Thin film gauge
Resistance vacuum gauge
Thin film gauge
Compression vacuum gauge
Ionization gauge
Lonization gauge

Before leaving the factory, vacuum pumps, vacuum pump sets, vacuum systems and various vacuum equipment need to measure the ultimate vacuum, working pressure and other vacuum degrees that they can achieve, and check according to relevant standards to see whether they meet the factory standards and work requirements.

In addition, after the vacuum equipment has been running for a period of time, due to various factors, certain failures and failures of the vacuum equipment will occur. Often the vacuum degree and pumping efficiency cannot meet the required requirements, and the related equipment needs to be maintained. This measures vacuum.

According to different application requirements and different vacuum pumps, there are corresponding vacuum measuring instruments (vacuum gauges).

When the vacuum degree does not meet the factory standard or working requirements, there is often a certain leak in the vacuum equipment, so it is necessary to check the relevant equipment and parts for leaks. In addition, in many important vacuum application fields, it is not only necessary to measure the degree of vacuum, but also to perform necessary leak detection on the vacuum pump, vacuum system, vacuum chamber and various components. The main leak detection methods are as follows:
Leak detection method Test medium Minimum detectable leak rate Pressure range Quantized value
Pa.L/S R134a g/a
Foam (soap method) Air 10-2 7.10-1 Positive pressure None
Ultrasound earpiece Air 100 70 Positive pressure None
Halogen leak detector Halogen gas 10-3 10-1 Positive pressure or vacuum  
Helium leak detector Helium 10-10 7.10-7 Vacuum Have
10-5 7.10-2 Positive pressure Have
Bubble method Air 10-1 7 Positive pressure None
Water pressure test Water 100 70 Positive pressure None
Static pressure drop method Air 10-2 7.10-1 Positive pressure Have
Static boost method Air 10-2 7.10-1 Vacuum Have
We can provide suitable leak detection services according to different applications and different equipment parts.