Follow the control sequence
Start with the working opening. Moving the sash changes the available opening area. A variable-volume control arrangement responds by changing exhaust airflow, with the aim of maintaining the intended operating conditions across its designed range.
SashDrive measures sash position and uses that information to regulate the fan. Its design has no bypass inlet above the sash. When used with the sash lowered, the cupboard extracts less room air.
This is a control principle, not a substitute for checking the complete installation. The fan, duct resistance, room air supply and controller setup all belong in the commissioning discussion.
Distinguish volume from face velocity
Air volume describes how much air moves through the system in a given time. Face velocity describes the speed through the working opening. They are related, but they are different measurements. Our face-velocity guide explains how to read the operating conditions alongside a reported value.
| Question | Why it matters |
|---|---|
| What changes the exhaust rate? | Identifies the signal and equipment being controlled. |
| What operating range is designed? | Defines the sash positions and process conditions to review. |
| How does room supply respond? | Connects cupboard extraction with the building ventilation. |
| How is a fault indicated? | Establishes the operator response and service information. |
Prepare realistic operating scenarios
Describe a normal working day: when the cupboard is attended, how it is loaded and which tasks need a particular opening. Include heat-producing equipment and any process that continues when the operator steps away.
For a room with several cupboards, record which may operate together. The building-services team needs this information to coordinate replacement air with extraction.
If energy use is part of the decision, take those same scenarios into the SashDrive energy-planning discussion. The actual use pattern is more useful than a saving assumed from the equipment name.
To compare an existing installation with a proposed change, build an energy-use operating record before estimating savings.
Ask for a clear handover
- Identify the cupboard, fan, controller and associated drawings.
- Record the agreed operating positions and relevant test conditions.
- Provide the user instructions and the site’s alarm-response procedure.
- Assign responsibility for faults, maintenance and changes to the process.
- Keep the final settings and commissioning records with the asset information.
Operators should use the controls described in their handbook. Changes to control settings or fan operation belong with the responsible technical team. For the equipment pairing, see the Fumeflow D250 product information.