Product / RMC

Halton RMC – Airflow management damper (CAV)

The Halton RMC is a high performance, mechanically actuated CAV airflow control damper designed to deliver reliable, energy efficient, and pressure independent airflow management.

It ensures precise ventilation across even the most complex duct systems. It maintains a consistent, independent airflow rate for both supply and exhaust applications, regardless of fluctuations in duct static pressure. It supports sustainability goals by optimising ventilation efficiency, minimising commissioning effort, and reducing ongoing energy consumption.

Constant airflow damper without external power supply, self-balancing operation
Large operation area, pressure range of 50…1000 Pa
Optimised volume flow control unit
Easy to read scale with volume flow indicator in m³/h and cfm

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Overview
Operating principle
Materials
Dimensions
Product models
Specification
Installation
Commissioning
Maintenance
Order Code
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Overview

The Halton RMC is a mechanical CAV damper with self- balancing operation. It does not require an external power supply and features a galvanised steel design. It features a large operating range of 50 to 600 Pa and is also available with a pressure range from 50 Pa to 1000 Pa.

Constant airflow damper without external power supply, self-balancing operation
Optimised volume flow control unit
Easy to read scale with volume flow indicator in m³/h and cfm

Product models

Models with and without insulated casing

Operating principle

The Halton RMC constant airflow damper is an independent control element operates without an external power supply, maintaining the required airflow rate regardless of upstream pressure changes. Consequently, system balancing is not needed.

As the dynamic pressure in the duct branch increases, the damper turns, thus increasing the pressure loss and preventing an excessive increase in the airflow rate. Similarly, as the dynamic pressure decreases, the spring returns the blade to the open position, reducing the pressure loss and maintaining a constant airflow rate.

The constant airflow damper includes a damper blade, supported by bearings and connected to an adjustment spring. As a result of the balance between aerodynamic forces and the spring effect, the necessary throttling effect is achieved, resulting in the set airflow rate.

Operation range

The constant airflow damper operates from a minimum pressure difference over the unit, which depends on the air velocity (see diagram below), to a maximum of 1000 Pa.

For example, if the air velocity in the duct is 7 m/s, the unit pressure loss is approximately 100 Pa or higher.

Size	q_v min.	q_v max	q_v min.	q_v max	v min.	v max	d_Pst min.*	d_Pst max
mm	m³/h	m³/h	l/s	l/s	m/s	m/s	Pa	Pa
80**	40	125	11	35	2.2	6.9	50	1000
100	70	220	19	56	2.5	7.1	50	1000
125	100	280	28	78	2.3	6.3	50	1000
160	180	500	50	139	2.5	6.9	50	1000
200	250	900	69	250	2.2	8.0	50	1000
250	500	1500	139	417	2.8	8.5	50	1000
315	800	2200	222	611	2.9	7.8	50	1000
355**	900	3200	250	889	2.5	9.0	50	1000
400	1000	3800	278	1250	2.2	8.4	50	1000

* Control inaccuracy less than 20%.
** New dimensions

Materials

No.	Part	Material
1	Housing	Galvanised steel
2	Damper blade	Aluminium
3	Damper blade bearings	PTFE
4	Tube for the adjustment	Plastic
5	Ring seals	Rubber

Dimensions

Halton RMC/N (without insulation)

Halton RMC/I (insulated)

NS [mm]	L [mm]	L1 [mm]	H [mm]	ØD [mm]
80*	165	40	75	79
100	165	40	75	99
125	165	40	75	124
160	235	40	75	159
200	235	40	75	199
250	235	40	75	249
315	225	60	110	314
355*	295	60	110	354
400	295	60	110	399

* New dimensions

Product models

Product model	Code	Description
Standard	N	No insulation
External insulation	I	Mineral wool, thickness 50 mm, for sound insulation and reduction of heat transfer

Specification

Function

The constant airflow damper operates without an external electrical or pneumatic
The damper operates with an adjustable spring.

Materials

The damper casing is made of galvanised steel.
The damper blade and attenuator is made of aluminium.
The damper casing is insulated with mineral wool as sound and heat insulation material (optional).

Structure

The damper with a manual adjustment device shall be easily set or reset on the work site during commissioning

Installation

The constant airflow management damper can be installed on both horizontal and vertical ducts. However, when installed in vertical ducts, the adjustable spring must be positioned horizontally.

Safety distances for the damper

The airflow control damper should be installed in an undisturbed airflow. The airflow velocity profile in the duct should be sufficiently even, without disturbances from bends, T-branches, etc.

The required safety distance after a bend or T-branch is 2.5 times the duct diameter.

The airflow control damper should be installed so that the arrow points in the direction of the airflow. See the installation examples below.

Commissioning

Each damper arrives pre-calibrated for optimal airflow efficiency based on its diameter. On-site airflow adjustments can be made easily within the control range:

For sizes 80 to 250, simply turn the control knob for quick and precise tuning, no tools required.
For sizes 315 to 400, use a screwdriver or Allen key to adjust the spring compression according to the clearly marked flow rate scale on the adjustment cylinder.

Maintenance

All components are designed to be maintenance‑free, non‑ageing, and corrosion‑resistant under normal operating conditions. Routine functional checks are generally unnecessary. However, accessibility for inspection and commissioning must be ensured in accordance with DIN EN 12097, which specifies access requirements for ventilation duct systems.

In standard applications, no further maintenance actions are required beyond ensuring that installation conditions and airflow profiles remain within the specified operating parameters.