1. The Direct Impact of Humidity on Physical and Chemical Analysis Instruments
The high humidity in the laboratory environment causes moisture to adhere to the surface of instruments, forming a continuous water film or condensing into droplets, which can adhere to circuit boards or components, resulting in redox reactions and reducing the safety and reliability of the circuits. If acidic or alkaline gases from industrial atmospheres dissolve in neutral water, the water becomes a weakly acidic or alkaline liquid, corroding instruments and circuit boards, leading to short circuits and reduced insulation functionality, resulting in unstable measurement values and rendering the instruments unusable. Water mist can also degrade the overall performance of optical systems and cause rust on mechanical components of light sources, leading to decreased smoothness of metal mirrors and causing rust and mold on aluminum films of optical components such as gratings, mirrors, and focusing lenses, resulting in insufficient light energy, stray light, and noise. This is particularly significant in the humid spring rainy season in southern regions. If the humidity of the laboratory environment where the equipment is stored is not monitored and effectively controlled during this period, the failure rate of the equipment significantly increases compared to normal conditions, affecting the lifespan of the instruments and potentially leading to equipment damage and inoperability.
For example, physical and chemical analysis instruments such as pH meters, spectrophotometers, conductivity meters, and polarimeters require sufficient warm-up time upon each startup. The stability of the instrument’s zero point and its repeatability can vary significantly, sometimes deviating greatly from the set values, with mechanical display instruments showing erratic needle movements or unidirectional shifts that cannot be adjusted; digital instruments may exhibit fluctuating or significantly deviating readings, with numbers oscillating without pattern. The main issue is that physical and chemical analysis instruments are significantly sensitive to humidity, and the equipment is often underutilized. If the laboratory is long-term closed without proper air conditioning or dehumidification equipment installed as per regulations, and if the laboratory is poorly located with long-term dark and humid conditions, high humidity, and poor ventilation, along with delayed and inadequate daily maintenance, the equipment failure rate will increase. A laboratory for controlling humidity throughout the seasons must be equipped with dehumidification and ventilation equipment.
2. The Sensitivity of Temperature on Physical and Chemical Analysis Instruments
When instruments are operating normally, they generate heat. If the ambient temperature is too high, heat dissipation is relatively slow and inefficient, causing various components installed within the machine to remain in an overheated state for extended periods, which can easily lead to aging, degradation, and damage, significantly shortening the equipment’s lifespan and causing frequent complex issues or failures. For instance, in a visible spectrophotometer that uses high-power tubes as a voltage regulator and tungsten lamps as light sources, if the ambient temperature is too high, it can lead to poor heat dissipation, resulting in breakdowns between the electrodes of the high-power tubes, causing the tungsten lamp to become overly bright, making the brightness potentiometer impossible to adjust to 100%. Over time, the lamp may overheat and burn out. Conversely, if the laboratory’s working environment is too cold, the warm-up time for instruments will be extended, and the rates of chemical reactions and detection data will lag, failing to accurately reflect measurement values.
Physical and chemical instruments are significantly affected by temperature. If the ambient temperature is too low, the instrument’s startup effect is poor. Some critical components are temperature-sensitive, such as certain electronic emission tubes that release generated ions or electrons, which may not fully achieve effective excitation, directly impacting the normal use of the instruments and causing distortion in detection data. For instance, the detection limit of an atomic fluorescence spectrometer typically requires maintaining the laboratory environment temperature around 26°C. If the temperature is too low (e.g., below 15°C), the characteristic spectral lines emitted by the excitation light source (usually a hollow cathode lamp or a non-polar discharge lamp) cannot effectively excite the atoms of the measured substance in the argon-hydrogen flame, leading to lower measured fluorescence values or nonlinear standard curves, resulting in detection parameter results deviating from normal values and misjudging nonconformity. Therefore, physical and chemical instruments have high requirements for the laboratory environment’s working temperature, which must be controlled according to operational specifications. A temperature-controlled laboratory must be equipped with constant temperature or temperature regulation equipment.
3. Dust and Smoke Prevention
Dust on the moving parts of instruments can increase wear, affecting the flexibility of mechanical systems and reducing the reliability of various limit switches, buttons, and optoelectronic couplers. Smoke and dust in the environment, along with corrosive gases in the atmosphere, can dissolve in water or mist, becoming corrosive liquids with certain acidity or oxidation properties, which can cause short circuits and leakage, and are also one of the causes of rust on optical components such as aluminum films. Over time, dust will accumulate inside instruments, necessitating regular cleaning to ensure environmental and hygienic conditions in the instrument room.
Dust and smoke prevention is generally standard equipment; qualified laboratory technicians can follow regulations for smoke isolation, effective discharge, and cleaning of the laboratory. For complex precision equipment, it is best to arrange for professional after-sales engineers from the equipment manufacturer to maintain or guide on-site, regularly opening the instrument covers to clean the internal circuit boards and optical components, calibrating the optical paths if necessary, cleaning and lubricating the mechanical parts, and re-tightening the heatsinks of all heating components before restoring the original state, followed by necessary testing, calibration, and documentation.
4. Vibration Control
For most precision equipment, vibration must be controlled, especially for measuring devices, as vibration can profoundly affect their accuracy. Vibration occurs under the influence of external forces and is a form of energy. Part of the vibrational energy radiates into space, creating air noise, while another part is transmitted through structural components to the measurement end or the measured object, causing a decrease in measurement accuracy. The sources of vibration can include steady-state vibrations from continuously running machinery, impact vibrations from sudden external forces, or disturbances from moving air, commonly referred to as sound radiation. Vibration isolation measures include controlling the vibration source to minimize vibrations, isolating the vibration source to block transmission paths, or altering the direction of the vibrations.
Vibration refers to tremors caused by natural environmental or external influences, resulting in one-time or multiple movements. Vibration isolation aims to overcome and avoid various disturbances caused by environmental or external factors, which can impact or damage laboratory instruments and equipment. The definitions of vibration and tremor are different and should not be confused. Currently, national regulations set technical requirements for laboratory environmental vibration projects, primarily to prevent mechanical vibrations from affecting measurement instruments.
5. Electromagnetic Interference
Precision instruments are highly sensitive to electromagnetic interference, which can manifest in various ways, causing measurement indicators to deviate from normal values, exhibit oscillations, or lead to errors in the control system’s operational logic, potentially resulting in loss of control or erroneous actions. Electromagnetic interference signals often drown out detection signals, reducing the signal-to-noise ratio of the equipment. Electromagnetic interference can alter the trajectory of signals (such as ionized ions, electron charges, charged particles, X-rays, atomic spectral lines, etc.), making it impossible to obtain accurate and reliable detection data. Methods to suppress electromagnetic interference include improving equipment design to overcome inherent electromagnetic interference, using shielding techniques to reduce electromagnetic interference, employing grounding techniques to eliminate electromagnetic interference, utilizing wiring techniques to improve electromagnetic interference, and applying filtering techniques to reduce electromagnetic interference.
6. Ionizing Radiation
Ionizing radiation includes natural radioactivity and isotopic radiation sources, emitting high-energy particles such as alpha rays, beta rays, gamma rays, and X-rays, which can damage human cells and interfere with and destroy all objects. This can cause various damage and interference to instruments due to penetrating radiation, leading to short circuits. Some instruments carry isotopic materials as normal measurement sources, and as long as these instruments are operated according to strict regulations, they are safe. However, strict rules must be established, and a special equipment management system must be implemented in laboratories to prohibit disassembly of relevant components without the permission of designated personnel or safety officers to prevent the leakage of radioactive sources and irreversible harm to the environment and personnel.
7. Ventilation and Safe Disposal
Safe discharge and harmless treatment of toxic and harmful gases or substances in the laboratory are primarily achieved by establishing reliable and efficient laboratory exhaust ventilation systems that effectively remove waste gases and introduce clean air. Toxic and harmful pollutants generated after use can be discharged through dedicated pollutant pipelines or collected and concentrated according to regulations, delivered to qualified institutions or companies with the capability to treat pollutants for harmless degradation, recycling, classification, and circular processing to avoid secondary pollution and eliminate secondary damage.
Through a comprehensive analysis of the impact of environmental factors on the use of physical and chemical instruments in the laboratory, many issues ultimately stem from staff negligence, failing to recognize the impact of environmental conditions on instruments, overusing while neglecting maintenance, and not paying attention to daily safety checks and equipment management. Being prepared and taking preventive measures is fundamental to managing laboratory environments and standardizing the use of physical and chemical analysis instruments.
This article was published in the “China Metrology” magazine, Issue 12, 2019.
Author: Huang Dongxing, Fujian Province Ningde City Metrology Institute
