Laboratory Monitoring and Control

Control strategies are key to lab and building occupant safety

Real Measurement Matters in Lab Controls

The use of chemicals and other potentially hazardous compounds separates laboratories from other types of building spaces. Keeping lab and building occupants safe must be the primary concern. Temperature and humidity control must be tightly controlled for occupant comfort and experiment integrity.

Laboratories typically have high ventilation, driven by fume hood exhaust flows and air change rates, to meet these concerns. But high ventilation causes high operating costs. In fact, laboratories use six times the energy of a similar office building. Energy-efficiency is of considerable importance to minimize operating costs.

Types of Fume Hood Controls and Laboratory Room Controls

Laboratories are normally maintained at a lower (negative) pressure than surrounding building areas help prevent contaminants from spreading throughout a building. Standard types of fume hood and laboratory control types are:

Good: Constant Volume (CV) Controls
Air volume supplied and exhausted does not change and remains constant 24/7. These systems are expensive to operate and limit future expansion.
Better: Variable Air Volume (VAV) Controls
Reduce airflows to the minimum required to maintain room pressure or balance, ventilation and temperature based on current conditions in the laboratory. These systems offer the greatest energy savings and best expandability in the future.

Top Choice—Types of VAV Laboratory Room Control Strategies

VAV Laboratory Room Control Strategies are top choice. In a laboratory using VAV controls, airflows supply and room exhaust airflows must change in response to fume hood exhaust and room temperature fluctuations. Typical room types and their recommended control strategies are:

Open Labs: Flow Tracking Controls
Offers the most stable airflow control, but controls laboratory balance instead of pressure differential. Exhaust more air than is supplied to maintain laboratory balance without measuring pressure differential. Recommended for:
- High-traffic laboratories
- Open laboratories without doors
- Laboratories of low to medium hazard
Enclosed Labs: Flow Tracking with Pressure Feedback Controls
Offers the stable airflow of flow tracking control with increased safety. This controller also measures the room pressure differential to warn of changing conditions. Recommended for:
- Laboratories with closed doors
- Laboratories of low to medium hazard
High Containment Labs: Direct Pressure Controls
Offers the most accurate control of room pressure differential, but supply and exhaust airflows may be less stable. Recommended for small laboratories of high hazard.

VAV Fume Hood Control Strategies

VAV fume hood controls are designed to maintain a constant face velocity, so the fume hood only exhausts the air necessary for containment. The two VAV fume hood controls options are:

Good: Sash Position Controls
Measures exhaust air volume and sash position to calculate face velocity.
Better: Sidewall Sensing Controls
Detects face velocity changes caused by sash position, user presence and equipment in a fume hood to maximize safety through real-time measurement.

VAV Laboratory Room Control Strategies

Types of VAV laboratory terminal devices are commonly used:

Good: Venturi Valves — High accuracy flow meters have a high pressure drop, making them expensive to operate.
Better: Dampers in Conjunction with Thermal Flow Stations — Best accuracy, with an actual measurement of airflow. Low-pressure drop dampers reduce operating expenses, but individual components can be more difficult to install.
Best: SACV — Terminal devices offer 100:1 turndown to simplify product selection and installation, while integral low-pressure drop dampers reduce operating expenses.