TROX RN schematic showing damper blade bellow and airflow setting scale

TROX RN circular self-powered constant volume controller

TROX RN – Round Constant Volume Regulator

Call for Price

For the precise control of constant volume flow rates

Circular self-powered volume flow controllers for the control of supply air or extract air in constant air volume systems

Volume flow rate can be set using an external scale, no tools required
High control accuracy
No on-site test measurements required for commissioning
Suitable for airflow velocities of up to 12 m/s
Any installation orientation; maintenance-free
Casing air leakage to EN 1751, class C

Optional equipment and accessories

Acoustic cladding for the reduction of case-radiated noise
Secondary silencer Type CA or CS for the reduction of air-regenerated noise
Hot water heat exchanger Type WL and electric air heater Type EL for reheating the airflow
Actuator for switching between setpoint values

Type

Acoustic cladding

setpoint valvue Nominal

Material

Flange

Nominal size [in]

Accessories

Actuator for setpoint valvue adjustment

Operating values for factory setting

SKU: RN Category: Constant Volume Regulators (CAV) Tag: RN

General Information

Application

Circular CONSTANTFLOW CAV controllers of Type RN for the precise supply air or extract air flow control in constant air volume systems
Mechanical self-acting volume flow control without auxiliary energy
Simplified project handling by ordering based on nominal size
The volume flow setpoint can be set on external scale
qᵥmin – qᵥmax-Switching with optional actuator

Special characteristics

Volume flow rate can be set using an external scale; no tools required
High volume flow rate control accuracy
Any installation orientation

Nominal sizes

RN: 3, 4, 5, 6, 8, 10, 12, 16
RN-S: 3, 4, 5
RN-FL: 4, 5, 6, 8, 10, 12, 16

Variants

RN: Volume flow controller in standard construction
RN-S: Volume flow controller with low installation height
RN-FL: Volume flow controller with flanges on both ends

Units with acoustic cladding for demanding acousti requirements

RN-D: Volume flow controller with acoustic cladding
RN-D-FL: Volume flow controller with acoustic cladding, both ends with flange
Acoustic cladding cannot be retrofitted

Construction

Galvanised sheet steel
P1: powder-coated surface, silver (RAL 7001)
A2: stainless steel

Parts and characteristics

Ready-to-commission controller
Damper blade with low-friction bearings
Bellows for vibration damping
Cam plate with leaf spring
Scale with pointer to set the volume flow setpoint
Aerodynamic functional testing of each unit on a special test rig before shipping
Perfect function even with unfavorable
upstream conditions (required straight upstream length 1.5D)

Attachments

Min/Max actuators: Actuators for switching between minimum and maximum volume flow rate setpoint values
Modulating actuators: Actuators for the infinite adjustment of volume flow rates or to switch between minimum and maximum volume flow rate setpoint values
Retrofit kits: Actuators and installation accessories
Variant RN-S cannot be combined with an actuator

Accessories

Lip seals on both ends (factory fitted)
Matching flanges for both ends

Useful additions

Circular silencers CA (for Germany and Switzerland) and CAH (for EMEA)
Heat exchanger Type WL
Electric air heater Type EL
Useful additions have to be ordered separately

Construction features

Circular casing
Spigot suitable for circular ducts to EN 1506 or EN 13180
Spigot with groove for lip seal (RN-P1/80 and RN-A2/80 are not available with groove/lip seal)
RN-FL: Flat face flanges to EN 12220

Materials and surfaces

Galvanised sheet steel variant
Casing made of galvanised sheet steel
Interior parts, nominal sizes 80 – 125: stainless steel 1.4301, nominal sizes 160 – 400: galvanised sheet steel
Polyurethane bellows
Plain bearings with PTFE coating
Leaf spring made of stainless steel

Powder-coated variant (P1)

Casing made of galvanised sheet steel, powder-coated
Interior parts, nominal sizes 80 – 125: stainless steel 1.4301, nominal sizes 160 – 400: galvanised sheet steel, powder-coated

Stainless steel variant (A2)

Casing made of stainless steel 1.4301
Interior parts made of stainless steel

Variant with acoustic cladding (-D)

Acoustic cladding made of galvanised sheet steel
Rubber seal for the insulation of structure-borne noise
Lining made of mineral wool

Mineral wool

According to EN 13501, fire rating class A1, noncombustible
RAL quality mark RAL-GZ 388
Harmless to health due to high biosolubility, according to TRGS 905 as well as EU Directive 97/69/EC

Standards and guidelines

Meets the hygiene requirements of VDI 6022
Casing air leakage according to EN 1751, class C

Maintenance

Maintenance-free as construction and materials are not subject to wear

Function

Functional description

The volume flow controller is a mechanical self-powered unit and works without external power supply. A damper blade with low-friction bearings is adjusted by aerodynamic forces such that the set volume flow rate is maintained within the differential pressure range.

The aerodynamic forces of the airflow create a closing torque on the damper blade. The bellows extends and increases this force while at the same time acting as an oscillation damper. The closing force is countered by a leaf spring that unrolls over a cam plate. The shape of the cam plate is such that a change in the differential pressure leads to an adjustment of the damper blade in a way that the volume flow rate is maintained almost exactly.

Efficient commissioning

The volume flow rate setpoint value can be set quickly and easily using the pointer on the external scale; no measurements are required.

The advantage over flow adjustment dampers is that there is no need for repeat measurements or adjustments by an air conditioning engineer. Should the system pressure change, e.g. by opening or closing of duct sections, the flow rates in the entire system will also change if flow adjustment dampers are used; however, this is not the case with mechanical self-powered volume flow controllers A mechanical self-powered controller reacts immediately and adjusts the damper blade such that the set constant volume flow rate is maintained.

Schematic Illustration of the RN

① Damper blade
② Bellows
③ Bellows inlet
④ Crossbar
⑤ Leaf spring
⑥ Cam plate
⑦ Volume flow rate scale lock
⑧ Volume flow rate scale
⑨ Lip seal

Specification Text

Circular volume flow controllers for constant air volume systems, mechanical self-powered, without external power supply, suitable for supply or extract air, available in 8 nominal sizes.

Ready-to-commission unit consists of the casing containing a damper blade with low-friction bearings, bellows, external cam plate and leaf spring.

Volume flow controllers without actuators are factory set to a reference volume flow rate (customers can set the required volume flow rate on site).

Spigot with groove for lip seal, suitable for connecting ducts according to EN 1506 or EN 13180.

Casing air leakage to EN 1751, class C.

Special features

Volume flow rate can be set using an external scale; no tools required
High volume flow rate control accuracy
Any installation orientation

Materials and surfaces

Galvanised sheet steel construction

Casing made of galvanised sheet steel
Interior parts, nominal sizes 3 – 5: stainless steel 1.4301, nominal sizes 6 – 16: galvanised sheet steel
Polyurethane bellows
Plain bearings with PTFE coating
Leaf spring made of stainless steel

Powder-coated construction (P1)

Casing made of galvanised sheet steel, powder-coated
Interior parts, nominal sizes 3 – 5: stainless steel 1.4301, nominal sizes 6 – 16: galvanised sheet steel, powder-coated

Stainless steel construction (A2)

Casing made of stainless steel 1.4301
Interior parts made of stainless steel

Variant with acoustic cladding (-D)

Acoustic cladding made of galvanised sheet steel
Rubber seal profile for the insulation of structure-borne noise
Lining is mineral wool

Mineral wool

To EN 13501, fire rating class A1, non-combustible
RAL quality mark RAL-GZ 388
Biosoluble and hence hygienically safe according to the German TRGS 905 (Technical Rules for Hazardous Substances) and EU directive 97/69/EC

Construction

Galvanised sheet steel
P1: Powder-coated, silver grey (RAL 7001)
A2: Stainless steel

Technical data

Nominal sizes: 3 to 16 in
Volume flow rate range: 24 to 2966 cfm
Volume flow rate control range: approx. 25 – 100 % of the nominal volume flow rate
Minimum differential pressure: 0.2 in WG (nominal size 3: 0.4 in WG)
Maximum differential pressure: 4.01 in WG

This specification text describes the general properties of the product. Texts for variants can be generated with our Easy Product Finder design programme.

Life cycle assessment
A life cycle assessment is available for the product series in form of an Environmental Product Declaration (EPD) that has been checked and published by a programme holder.