What are the Precautions for Using Vacuum Gauges?

As the core equipment for measuring vacuum degree, the measurement accuracy and stability of a vacuum gauge directly affect the quality of experiments or production processes. To ensure equipment safe operation and obtain reliable data, the following points need special attention during use:

I. Installation Environment and Location Selection

1. Avoid Interference Sources: Keep away from heat sources such as vacuum pump exhaust ports and heating furnaces, as well as strong magnetic field equipment like large motors and transformers. Turbulent airflow areas can cause measurement value fluctuations; local pressure changes induced by heat sources can reduce accuracy; strong magnetic fields may interfere with electronic circuits.

2. Optimize Observation Conditions: The installation height should conform to the operator's line of sight habits, with sufficient operating space reserved. For example, in semiconductor manufacturing equipment, vacuum gauges are often installed on the side of the chamber for real-time monitoring and to avoid contamination by process materials.

3. Piping Design Specifications: Connection pipes should be short and thick with matching inner diameters; avoid using long and thin pipes. For instance, in a vacuum furnace renovation case, replacing the original 2-meter thin pipe with a 0.5-meter thick pipe reduced the measurement response time by 60%.

II. Operation Standards and Safety Protection

1. Range Matching Principle: Select the appropriate range according to the measurement range. For example, the HPM4/6 vacuum gauge ranges are divided into 0.001-1.0 Torr (for cryogenic containers) and 0.01-20.0 Torr. Using beyond the range can cause permanent sensor damage.

2. Dynamic Process Control: After starting the vacuum pump, wait for the system to stabilize before taking readings. In a certain aerospace material experiment, failure to wait for vacuum stability resulted in a measurement deviation of 35%. For compression vacuum gauges, raise the mercury column slowly and steadily, pausing for adjustment when approaching the reference line.

3. Anti-Contamination Measures: After using a McLeod gauge, immediately return it to the horizontal position and tighten the rubber tube to prevent pump oil backflow. A chemical company failed to perform this operation, resulting in mercury contamination of the vacuum gauge and increasing maintenance costs by 20,000 yuan.

III. Maintenance and Calibration Management

1. Regular Cleaning and Inspection: Wipe the sensor surface weekly with a lint-free cloth dipped in anhydrous ethanol; monthly check the sealing of connecting cables. A semiconductor production line failed to replace an aging seal in time, causing an annual leakage rate exceeding the standard by 0.5 Pa.

2. Calibration Cycle Control: Resistance vacuum gauges are recommended to be calibrated every 6 months; ionization vacuum gauges require zero-point calibration every 3 months. An optical laboratory failed to calibrate regularly, resulting in a coating thickness deviation of 12%.

3. Storage Environment Requirements: When storing for a long time, place in a dry cabinet with relative humidity controlled at ≤45%. A research institution stored the vacuum gauge in a humid environment, leading to circuit board corrosion and a 2-week repair time.