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Halton TRI – Plenum for diffusers (terminated)

Terminated as of 1st July 2023
->  replaced with Halton Pop PDI

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Terminated as of 1st July 2023
->  replaced with Halton Pop PDI

  • Plenum for connecting ceiling diffuser/exhaust unit to ductwork
  • Ensures proper function of the supply air diffuser
  • Airtight, robust construction with aesthetically pleasing design
  • Flexibility for levelling diffuser elevation
  • Detachable measurement and airflow rate adjustment module
  • Effective sound attenuation
  • Access for ductwork cleaning

 Product models

  • Model for active diffusers

Dimensions and weight

100/100 308 152 67 282 99 102
100/125 308 152 67 282 99 127
100/160 308 152 67 282 99 162
125/125 458 182 67 432 124 127
125/160 458 182 67 432 124 162
125/200 458 182 67 432 124 202
125/250 458 182 67 432 124 252
160/160 458 222 67 432 159 162
160/200 458 222 67 432 159 202
160/250 458 222 67 432 159 252
200/200 618 272 67 592 199 202
200/250 618 272 67 592 199 252
200/315 618 272 67 592 199 317
200/400 618 272 67 592 199 402
250/250 618 336 67 592 249 252
250/315 618 336 67 592 249 317
250/400 618 336 67 592 249 402
315/315 618 382 67 592 314 317
315/400 618 382 67 592 314 402


Halton TRI/S  + MSM

NS Weight (kg)
100/125 2.19
100/160 2.30
125/125 4.04
125/160 4.05
125/250 4.19
160/160 4.40
160/200 4.60
160/250 4.55
200/200 9.39
200/250 9.62
200/400 9.67
250/250 10.76
250/315 10.90
250/400 11.09


Part Material Note
Casing Galvanised steel
Collar Galvanised steel
Attenuation material Polyester fibre
Spigot with gasket Galvanised steel Gasket rubber compound
Measurement and
adjustment module
Body: Aluminium
Plate: Galvanised steel
Brackets: Galvanised steel
Plastic parts: Polypropylene (PP)
Spindle: Stainless steel
Junction box Plastic
Hanging and
safety wire


Accessory Code Description
Airflow measurement and
adjustment unit
MSM Adjustment and measurement
module for supply airflow rate
 Airflow adjustment unit MEM Adjustment module for
exhaust airflow rate
Sound attenuation IN Internal sound attenuation material of polyester fibre

Product models

 Model  Description
 TRI/S Balancing plenum for supply air with adjustment and
measurement module MSM and internal sound attenuation material
 TRI/E Balancing plenum for exhaust air with adjustment module MEM
and internal sound attenuation material
 TRI/N Balancing plenum for supply or exhaust air  without adjustment and
measurement module and internal sound attenuation material
 TRI/V Balancing plenum for active supply air diffusers with adjustment and
measurement module MSM and internal sound attenuation material.
Available only for sizes 160-160, 200-200 and 250-250.

Fig.1.  Halton TRI/S, E and N

Fig.2.  Halton TRI/V


  • Halton TRI balancing plenum equalises the airflow by reducing the flow velocity
  • Air is spread evenly into the diffuser ensuring proper function
  • A range of diffusers can be connected to the distribution ductwork using Halton TRI-plenum, which improves their functional characteristics considerably
  • The balancing plenum also attenuates duct noise
  • Halton TRI plenum can also be used as an exhaust unit.

The technical performance is presented for installation with the collar connected outside (Halton TRI-(N)) the balancing plenum.


Halton TRI plenum can be installed using two strips or with M8 drop rods (not supplied).

Halton TRI is connected to the distribution ductwork with a spigot equipped with an integral gasket.

Due to the modular collar system, the diffuser can be connected to the plenum in three different ways:

  • The collar connected to the outside of the plenum box
  • The collar mounted internally
  • Directly to the plenum without collar (possible only in limited cases).

In order to change the connection method, the collar is detached by opening the brackets and the collar is remounted into the desired position.

Halton TRI/V

The Halton TRI/V is connected to the ventilation ductwork with a male inlet connection.
After the ductwork pressure test, the diffuser can be installed.

Hang the diffuser to the wire of the Halton TRI/V plenum.
Connect the actuator cable connector plug to the plug from the plenum junction box.

Fix the actuator assembly to the plenum and tighten two screws.
The power supply and control signal cables are connected to junction box according to the diffuser’s wiring instructions.


The supply flow rate is determined by using the measurement and adjustment module MSM.
The tubes and control spindle are passed through the diffuser. Measure the differential pressure with a manometer. The flow rate is calculated using the formula below:

∆pm      Measured pressure [Pa]
k           The k factor given as a function of mounting and diameter
qv          Airflow rate [l/s]

The k-factor for installations with different safety distances
(D = duct diameter)

TRI > 8xD min. 3xD
100 6.0 7.5
125 9.9 12.6
160 16.9 21.9
200 28.3 32.0
250 47.9 51.5

Adjust the airflow rate by rotating the control s pindle until the desired setting is achieved.
Lock the damper position with a screw. Replace the tubes and spindle into the plenum.

When Halton TRI is used for exhaust air, it is not possible to measure airflow rate with adjustment module MEM.


Open or detach the diffuser. Detach the measurement and adjustment module by pulling gently from the casing (not from the control spindle or measurement tubes). Wipe the parts with a damp cloth, instead of immersing in water.

The measurement and adjustment module is remounted by pushing the body until it meets the stopper.
The sound attenuation material within the plenum can also be removed (the material is washable), to enable cleaning of the inner side of the plenum.

The material is detached by releasing the retaining brackets, which are replaced after washing.

Close or replace the diffuser after cleaning.


The balancing plenum is made of galvanised steel and has a robust and airtight construction.
The airflow rate measurement and adjustment module are available for supply application. The measurement and adjustment module is adjustable without opening the device.

The balancing plenum has a spigot with integral gasket for airtight duct connection and a plug for ductwork pressure testing.
The balancing plenum attenuates duct noise. The sound attenuation material is made of polyester fibre with a washable surface.

Order code


S = Model
S     Supply (MSM-module,sound attenuation)
E     Exhaust (MEM-module,sound attenuation)
N     Naked  (Model without MSM or MEM-module,sound attenuation)
V     Demand based model for active diffusers
(only sizes 160-160, 200-200 and 250-250)

D = Duct connetion size (mm)
100, 125, 160, 200, 315

E = Diffuser connection size (mm)
100, 125, 160, 200, 250, 315, 400

Other options and accessories

AC = Accessories
MSM     Measurement and adjustment module, supply
MEM     Adjustment module, exhaust
MS1      MSM with adjusting spin.L=1500
ME1      MEM with adjusting spin.L=1500
IN          Sound attenuation material

ZT  = Tailored product
N           No
Y           Yes (ETO)

Code example

TRI/S-100-100; ZT=N


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