Comprehensive Analysis of Design and Construction Process for Constant Temperature and Humidity Purification Laboratory: From Planning to Implementation

In fields with extremely high environmental requirements such as biomedicine, electronic information, and precision instrument testing, constant temperature and humidity purification laboratories are core infrastructures that ensure the accuracy of experimental data and the stability of product quality. These laboratories not only require precise control of temperature and humidity but also must achieve stringent air purification levels. The professionalism in their design and construction directly determines their subsequent operational effectiveness. Below, we will comprehensively analyze the entire construction process of constant temperature and humidity purification laboratories from four dimensions: design principles, core system design, key construction stages, and acceptance standards.

1. Core Principles of Constant Temperature and Humidity Purification Laboratory Design

The design of constant temperature and humidity purification laboratories must follow four major principles: "functionality first, systematic coordination, safety and reliability, and economic rationality." It must meet the special needs of experimental scenarios while balancing long-term operational stability and cost control.

First, Functional Adaptation is fundamental. Constant temperature and humidity purification laboratories in different industries have significantly different parameter requirements: in the biomedicine field, such laboratories usually need to control temperature between 20 - 25°C, maintain humidity at 45% - 65%, and ensure air cleanliness reaches Class 7 (ISO 14644-1 standard) or above to avoid microbial contamination affecting cell culture or reagent stability; in the electronics industry, the focus is more on controlling temperature fluctuations (within ±0.5°C) and maintaining a low humidity environment (30% - 40%) to prevent static interference with precision component production. During design, core parameters such as experimental processes, equipment power, and personnel numbers must be clearly defined to ensure that environmental control in each area precisely matches actual needs.

Second, Systematic Coordination is key. A constant temperature and humidity purification laboratory is not just a collection of individual devices but an organic whole composed of air conditioning purification systems, ventilation systems, automatic control systems, power distribution systems, and more. For example, the air supply volume of the air conditioning purification system must dynamically balance with the exhaust volume of the ventilation system to avoid pressure differences that could compromise the sealed environment of the clean area; the automatic control system must collect real-time data on temperature, humidity, cleanliness, and pressure differences, and coordinate adjustments of air conditioning units, humidifiers, dehumidifiers, and other equipment to ensure environmental parameters remain stable within set ranges. During the design phase, full system simulation calculations must be conducted to avoid "functional conflicts" between subsystems.

Additionally, Safety and Economic Considerations must be considered simultaneously. The electrical design of constant temperature and humidity purification laboratories must comply with explosion-proof and leakage prevention standards, especially in areas involving flammable and explosive reagents; fire protection systems must use dust-free extinguishers to avoid secondary contamination of the clean environment during firefighting. At the same time, by optimizing airflow organization (such as using top supply and side return airflow patterns) and selecting energy-efficient constant temperature and humidity units, long-term operational energy consumption can be reduced, achieving the goal of "reasonable initial construction investment and controllable subsequent operating costs."

2. Key Design Points of Core Systems in Constant Temperature and Humidity Purification Laboratories

(1) Air Conditioning Purification System: The "Heart" of Environmental Control

The air conditioning purification system is the core for achieving temperature and humidity regulation and air purification in constant temperature and humidity purification laboratories. Its design must focus on three aspects:

First, Temperature and Humidity Control Accuracy According to the laboratory grade, select appropriate constant temperature and humidity units. For example, high-precision laboratories requiring temperature and humidity fluctuations within ±0.5°C/±5% RH need units equipped with two-stage refrigeration and proportional-integral-derivative (PID) control functions. These units dynamically adjust cooling, heating, and humidification based on real-time environmental parameter sensing to avoid "overshoot" or "lag" phenomena. Additionally, flow equalizing plates should be installed at the unit air outlets to ensure uniform airflow delivery to each area, reducing local temperature and humidity differences.

Second, Air Purification Level Determine the air filtration process based on experimental needs. A common purification scheme is "primary filtration → medium filtration → high-efficiency filtration (HEPA)": primary filters (G4 grade) remove large particles (≥5μm) to protect subsequent medium filters; medium filters (F8 grade) filter medium particles (≥1μm) to reduce the load on high-efficiency filters; high-efficiency filters (H13 grade and above) are installed at clean area air supply outlets to capture particles ≥0.3μm, ensuring supply air cleanliness standards. Design must calculate air change rates (e.g., Class 7 clean areas require ≥15 air changes per hour), determine fan airflow based on laboratory volume, and ensure the face velocity of high-efficiency filters is controlled between 0.3 - 0.5 m/s to avoid excessive airflow affecting filtration efficiency.

Third, Airflow Organization Design Reasonable airflow organization effectively avoids "dead zones" and "vortices" within clean areas, ensuring uniform overall cleanliness. For larger constant temperature and humidity purification laboratories, it is recommended to use a "top supply and side return" airflow pattern: clean air is vertically delivered downward from high-efficiency supply outlets in the ceiling, forming a stable "clean airflow layer" in the laboratory bench area. Polluted air is exhausted from return air outlets located at the lower side walls, purified, and then recirculated indoors. If there are local high-pollution areas (such as biological safety cabinet operation zones), dedicated exhaust outlets should be set nearby to directly discharge pollutants outdoors through negative pressure control, preventing diffusion.

(2) Automatic Control System: Enabling Intelligent Operation and Maintenance

The automatic control system of constant temperature and humidity purification laboratories acts as the "brain," requiring real-time monitoring, automatic adjustment, and fault alarm functions. Industrial-grade PLCs (programmable logic controllers) should be selected as the control core, paired with high-precision temperature and humidity sensors (accuracy ±0.1°C/±1% RH), pressure difference sensors (accuracy ±5Pa), particle counters, and other detection equipment to achieve 24-hour continuous monitoring of key parameters.

When temperature or humidity deviates from set values, the automatic control system automatically sends adjustment commands to the constant temperature and humidity units: for example, when humidity exceeds the upper limit, the dehumidification function is activated while reducing humidification; when temperature falls below the lower limit, heating power is automatically increased. In case of equipment failure (such as fan shutdown or filter blockage), the system immediately triggers audible and visual alarms and notifies maintenance personnel via SMS, app push notifications, etc., while activating backup equipment (such as standby fans) to ensure environmental parameters do not fluctuate significantly in a short time. Additionally, the automatic control system should have data storage and analysis functions, automatically generating temperature, humidity, and cleanliness trend curves to provide data support for laboratory compliance audits (such as GMP certification).

(3) Power Distribution and Ventilation Systems: Ensuring Safety and Comfort

The power distribution system design must meet the high load and high stability requirements of the constant temperature and humidity clean laboratory. The distribution capacity is determined based on the total equipment power (including constant temperature and humidity units, laboratory equipment, lighting, etc.). An independent three-phase five-wire power supply is used, with dedicated distribution cabinets equipped with overload protection, leakage protection, and surge protectors to prevent voltage fluctuations from damaging precision equipment. At the same time, dustproof and waterproof embedded sockets are used in the clean area, with a 20% redundancy reserved for the number of sockets to facilitate future equipment additions.

The ventilation system must balance "pollutant exhaust" and "personnel comfort." For laboratory areas producing harmful gases (such as chemical reagent vapors), a local exhaust system must be installed, for example, a universal exhaust hood above the laboratory bench. The suction air velocity at the hood's intake is controlled between 0.5 - 1.0 m/s to ensure effective capture of harmful gases. The exhaust outlet must be equipped with an activated carbon filter to adsorb harmful gases before discharge, preventing environmental pollution. Additionally, the exhaust volume of the ventilation system must balance with the air supply volume of the air conditioning purification system to maintain a slight positive pressure (relative to outdoors, positive pressure controlled at 5 - 10 Pa) inside the constant temperature and humidity clean laboratory, preventing infiltration of unpurified outdoor air.

3. Key Stages and Quality Control in the Construction of Constant Temperature and Humidity Clean Laboratories

(1) Pre-construction Preparation: Establishing a Compliance Foundation

Before construction of the constant temperature and humidity clean laboratory, three core tasks must be completed: first, Deepening Design Drawing Review , organizing design, construction, supervision, and users to jointly participate in drawing reviews, focusing on verifying whether the airflow organization of the air conditioning purification system, the linkage logic of the automatic control system, and the load calculation of the power distribution system comply with standards and requirements to avoid rework caused by drawing omissions; second, Verification of Construction Team Qualifications , selecting teams with professional purification engineering contracting qualifications and experience in similar laboratory construction to ensure that construction personnel are familiar with the special requirements of clean area construction (such as dustproof and anti-static measures); third, Material and Equipment Acceptance , all incoming materials (such as clean color steel plates, high-efficiency filters) and equipment (such as constant temperature and humidity units, PLC controllers) must provide manufacturer qualification documents and test reports, and undergo sampling inspection. For example, high-efficiency filters must undergo integrity testing (bubble point method) and can only be used after confirming no leakage.

(2) Main Structure Construction: Strict Control of Cleanliness and Sealing

The core of the main structure construction is to create a "clean, sealed, and flat" laboratory space. Walls and ceilings use 50mm thick color steel plates (core material is rock wool or polyurethane, with fireproof and insulation properties). The joints between color steel plates must be coated with special sealant and reinforced with aluminum profiles to prevent air leakage. The floor uses epoxy resin self-leveling flooring. During construction, the base layer must be ground and dust removed, then primer and intermediate coatings applied, and finally the self-leveling layer spread to ensure floor flatness error ≤ 2mm/m, with chemical corrosion resistance and anti-static properties.

Doors and windows must meet clean area requirements: clean doors are made of stainless steel, equipped with door closers and sealing strips to ensure no gaps when closed; observation windows use double-layer insulated tempered glass, sealed with sealant between the glass and color steel plate to prevent condensation or air leakage. During construction, "zoned cleaning" measures must be taken, with dust and waste cleaned immediately after each construction area is completed to avoid cross-contamination and create a clean environment for subsequent purification system installation.

(3) Core System Installation and Commissioning: Ensuring Functional Implementation

During installation of the air conditioning purification system, ducts must be made of galvanized steel plates, with duct joints sealed with sealant. After installation, light leakage detection (no more than 2 light leakage points per 10m of duct) and air leakage rate testing (leakage rate ≤ 1%) must be conducted. Installation of high-efficiency filters is critical and must be done after cleaning the clean area's floor and walls. Before installation, the inside of the ducts must be cleaned again. The filter and air outlet frame are pressed tightly with sealing gaskets (such as neoprene rubber gaskets) to ensure no leakage.

The automatic control system installation must pay attention to sensor placement: temperature and humidity sensors should be placed away from air supply outlets, heat sources, and doors/windows to avoid local environmental interference causing data distortion; differential pressure sensors must be installed on walls between clean and non-clean areas and between different clean grade areas to monitor pressure differences in real time. System commissioning is divided into three stages: single machine debugging (testing the operation status of constant temperature and humidity units, fans, pumps, etc. one by one), linkage debugging (testing whether the automatic control system's linkage logic with each device is normal), and full system debugging (continuous operation for 72 hours, monitoring temperature, humidity, cleanliness, pressure difference, and other parameters for stability and compliance).

(4) Post-construction Cleaning and Disinfection: Ensuring Cleanliness Compliance

After construction of the constant temperature and humidity clean laboratory is completed, thorough cleaning and disinfection must be performed to remove construction residual dust, oil stains, and microorganisms. The cleaning process follows the principle of "inside to outside, top to bottom": first wipe dust from walls, ceilings, and equipment surfaces with lint-free cloths, then clean the floor with neutral detergent, and finally rinse with deionized water to ensure no detergent residue. Disinfection is performed using ultraviolet irradiation (dose ≥ 1.5 W·h per square meter) or hydrogen peroxide fumigation to sterilize the entire clean area. After disinfection, microbial testing (such as sedimentation bacteria test, Class 7 clean area ≤ 35 cfu/plate) must be conducted to confirm compliance with cleanliness grade requirements.

4. Acceptance Standards and Subsequent Operation and Maintenance of Constant Temperature and Humidity Clean Laboratories

(1) Acceptance Standards: Multi-dimensional Verification of Compliance

Acceptance of constant temperature and humidity clean laboratories must be based on relevant national standards (such as GB 50457-2019 "Design Standards for Pharmaceutical Industry Cleanrooms", GB/T 25915.1-2010 "Cleanrooms and Associated Controlled Environments Part 1: Air Cleanliness Classes"), carried out from four dimensions:

First, Temperature, Humidity, and Accuracy Acceptance At least 9 monitoring points are evenly arranged within the clean area (add 1 point for every additional 20㎡ if the area exceeds 50㎡), continuously monitored for 48 hours, recording hourly temperature and humidity data to ensure the average value meets design requirements and the fluctuation range does not exceed the set accuracy (e.g., ±0.5℃/±5% RH).

Second, Cleanliness Acceptance Using a laser particle counter to detect at different indoor heights (0.8m and 1.5m), each monitoring point is tested for no less than 1 minute, counting particle concentrations ≥0.3μm and ≥5μm, which must meet the limits of the corresponding cleanliness level (e.g., Class 7 clean area ≥0.3μm particles ≤352000pc/m³, ≥5μm particles ≤2930pc/m³).

Third, Pressure Difference and Airflow Organization Acceptance Use a differential pressure meter to detect the pressure difference between clean and non-clean areas and between different cleanliness level zones, confirming that the positive pressure value meets design requirements (5 - 10Pa); observe airflow direction through smoke testing to ensure no vortices or dead zones, and that airflow organization complies with the design plan.

Fourth, System Function Acceptance Test the alarm function of the automatic control system (e.g., simulate temperature and humidity exceeding limits, equipment failure, and check if alarms are timely), data storage and export functions; test the exhaust effect of the ventilation system (e.g., check the suction efficiency of the universal exhaust hood) to ensure all system functions operate normally.

(2) Post-operation and Maintenance: Extending Laboratory Service Life

Post-operation and maintenance of constant temperature and humidity purification laboratories are key to ensuring their long-term stable operation, requiring the establishment of a comprehensive maintenance system:

First, Regular Inspection and Maintenance Weekly inspection of the operation status of constant temperature and humidity units, fans, automatic control systems, and other equipment; monthly cleaning of primary filters; replacement of medium-efficiency filters every 3-6 months; annual integrity testing of high-efficiency filters, with immediate replacement if leakage is found; calibration of temperature and humidity sensors and differential pressure sensors every six months to ensure accurate detection data.

Second, Daily Environmental Monitoring Assign dedicated personnel to record laboratory temperature, humidity, and pressure difference data daily; conduct regular cleanliness testing (e.g., monthly sedimentation bacteria testing); promptly investigate causes if parameters are abnormal (e.g., filter blockage may cause cleanliness decline, humidifier failure may cause low humidity).

Third, Emergency Response Plan Develop emergency plans for equipment failure, power outages, fires, and other emergencies, such as equipping backup generators to ensure key equipment in the constant temperature and humidity purification laboratory (e.g., constant temperature and humidity units, biosafety cabinets) can operate for a short period during power outages; regularly organize emergency drills to improve maintenance personnel's emergency response capabilities.

The design and construction of constant temperature and humidity purification laboratories is a systematic project integrating professional knowledge, technical experience, and refined management. From early parameter planning and system design, through mid-term construction quality control and system commissioning, to later acceptance and maintenance, every step must be strictly controlled. Only by following scientific design principles, adopting professional construction techniques, and establishing a comprehensive maintenance system can a constant temperature and humidity purification laboratory be created that meets experimental needs, is stable and reliable, and economically efficient, providing a solid environmental guarantee for scientific research innovation and product development.