CAT CLASS: HQ-10462

Up to 1,000 cfm Confined Space Ventilator

Up to 1,000 cfm confined space ventilators supply forced air to manholes, vaults, and small tanks where short duct runs and limited air volume changes are sufficient. This is the smallest rung on the confined space ventilator ladder, designed for entry-level ventilation requirements. For larger spaces or longer duct runs, the industry steps up to 1,000-2,000 cfm units.

Models

Brands

Cat classes

Pick a size class — capacity and reach differ across the range.

Key specifications

Specification	Typical range	What it means
Airflow capacity	Up to 1,000 cfm	Maximum volumetric flow rate for ventilating the confined space.
Duct diameter	8–12 in (20.3–30.5 cm)	Fits standard flexible ducting for manhole and vault entry points.
Power configuration	115V or 230V single-phase	Standard electrical service required for most models in this size class.
Unit weight	30–60 lb (13.6–27.2 kg)	Light enough for one-person transport to the work site.

How to choose

This size class is appropriate for ventilating manholes, small vaults, and tanks with volumes under approximately 3,000 cubic feet, or where duct runs remain under 25 feet. It provides sufficient air changes for single-entry portals with minimal static pressure loss. For larger confined spaces, deeper vaults, or duct runs exceeding 25 feet, the 1,000-2,000 cfm Confined Space Ventilator class delivers higher flow rates and overcomes greater static resistance. This smallest class is chosen when space constraints, power availability, or the ventilation volume required do not justify a larger unit.

What this size handles

Manhole entry ventilation for utility inspection and maintenance
Vault ventilation for telecommunications or electrical equipment access
Small underground storage tank purging before hot work
Sewer lateral entry where a single access point requires air supply
Trench box ventilation on shallow excavations with limited headroom
Small pump station wet well ventilation during pump servicing

Safety & operation

Air monitoring is required before and during ventilation; ventilators do not replace atmospheric testing
Ducting must be positioned to avoid recirculating contaminated air back into the confined space
Units must be grounded and protected from water ingress in wet or flooded environments
Ventilator intake must draw from a clean air source, free of exhaust fumes or other contaminants

Transport & logistics

One person carries the unit to the work site; weight typically 30–60 lb
Fits in a service van or pickup bed without specialized securing
Flexible ducting transports separately, often coiled in 25 ft sections

Power & supply

Most models operate on standard 115V single-phase power from a site circuit or portable generator
Some higher-output models in this class require 230V single-phase service
Cord lengths typically 10–25 ft; extension cords must meet amperage and grounding requirements

Frequently asked

How is airflow capacity (cfm) determined for confined space ventilation?

Capacity is selected based on the volume of the confined space and the number of air changes per hour required by safety standards or site-specific hazard assessment. A common baseline is 6–10 air changes per hour; a 600 cubic foot space would require 600–1,000 cfm.

What limits the effective duct length for this size class?

Static pressure loss increases with duct length and bends; units in this class typically maintain effective ventilation on straight runs up to 25 feet. Longer runs or multiple bends reduce airflow and may require stepping up to a higher-capacity ventilator.

Can this size class be used for exhaust ventilation instead of supply?

Yes, many models can reverse airflow direction or be oriented to exhaust contaminated air from the confined space. The choice between supply and exhaust depends on the hazard type and whether positive or negative pressure is preferred.