DESIGN BULLETIN

ISSUE DATE:

30th August 2007 SUBJECT:

Supply & Return Air DiffusersVOLUME DISC SERIES NO.

REVISION:

00 5 M 300 001

Purpose :

This bulletine is being issued, to standardize the sizing and references of supply and return diffusers. The sizes mentioned below are only for guidance.

This standardization will be implemented on all future projects.

Description:

The Square type diffusers will be referenced as follows;

Type of DiffuserReference

of Diffuser

Neck Size of

Diffuser

Maximum Recommended Air flow

For Diffuser

Supply and Return Air Square Diffuser – 4 way SD4 - A / RD4 - A 150 x 150 50.0 l/s

Supply and Return Air Square Diffuser – 4 way SD4 - B / RD4 - B 225 x 225 100.0 l/s

Supply and Return Air Square Diffuser – 4 way SD4 - C / RD4 - C 300 x 300 180.0 l/s

Supply and Return Air Square Diffuser – 4 way SD4 - D / RD4 - D 375 x 375 260.0 l/s

Supply and Return Air Square Diffuser – 4 way SD4 - E / RD4 - E 450 x 450 350.0 l/s

Supply and Return Air Square Diffuser – 4 way SD4 - F / RD4 - F 600 x 600 500.0 l/s

Halcrow YollesPO Box 360 Dubai United Arab Emirates

Tel +971 43 3370380 Fax +971 43 3379239halcrowyolles.com

DESIGN BULLETIN

ISSUE DATE:

30th August 2007 SUBJECT:

Supply & Return Air DiffusersVOLUME DISC SERIES NO.

REVISION:

00 5 M 300 001

The Slot type diffusers will be referenced as follows;

The Square Egg Crate type diffusers will be referenced as follows;

Type of Diffuser Reference of Diffuser

Neck Size of Diffuser

Maximum Recommended Air flow For Diffuser

Egg Crate Square Diffuser EC 4 - A 150 x 150 50.0 l/s

Egg Crate Square Diffuser EC 4 - B 225 x 225 100.0 l/s

Egg Crate Square Diffuser EC 4 - C 300 x 300 180.0 l/s

Egg Crate Square Diffuser EC 4 - D 375 x 375 280.0 l/s

Egg Crate Square Diffuser EC 4 - E 450 x 450 410.0 l/s

Halcrow YollesPO Box 360 Dubai United Arab Emirates

Tel +971 43 3370380 Fax +971 43 3379239halcrowyolles.com

Type of DiffuserReference

of Diffuser

Number of

20 mm Slots

Maximum Recommended Air flow

Per meter length of diffuser, based on 20mm slot width

Supply and Return Linear Slot Diffuser – 1 Slot SLD - 1 One 30.0 l/s

Supply and Return Linear Slot Diffuser – 2 Slot SLD - 2 Two 60.0 l/s

Supply and Return Linear Slot Diffuser – 3 Slot SLD - 3 Three 90.0 l/s

Supply and Return Linear Slot Diffuser – 4 Slot SLD - 4 Four 120.0 l/s

Supply and Return Linear Slot Diffuser – 5 Slot SLD - 5 Five 150.0 l/s

Supply and Return Linear Slot Diffuser – 6 Slot SLD - 6 Six 180.0 l/s

DESIGN BULLETIN

ISSUE DATE:

30th August 2007 SUBJECT:

Supply & Return Air DiffusersVOLUME DISC SERIES NO.

REVISION:

00 5 M 300 001

Egg Crate Square Diffuser EC 4 - F 600 x 600 730.0 l/s

The Circular type diffusers will be referenced as follows;

Type of DiffuserReference

of Diffuser

Neck Size of

Diffuser

Maximum Recommended Air flow

For Diffuser

Supply and Return Air Circular Diffuser CDS4 - A / CDR4 - A 150 50.0 l/s

Supply and Return Air Circular Diffuser CDS4 - B / CDR4 - B 200 80.0 l/s

Supply and Return Air Circular Diffuser CDS4 - C / CDR4 - C 250 125.0 l/s

Supply and Return Air Circular Diffuser CDS4 - D / CDR4 - D 300 180.0 l/s

Supply and Return Air Circular Diffuser CDS4 - E / CDR4 - E 350 230.0 l/s

Supply and Return Air Circular Diffuser CDS4 - F / CDR4 - F 400 300.0 l/s

The Circular Disc Valve for toilet extract air will be referenced as follows;

Type of DiffuserReference

of Disc Valve

Neck Size of

Disc Valve

Maximum Recommended Air flow

For Disc Valve

Supply and Extract Air Disc Valve SDV - A / EDV - A 80 50.0 l/s

Supply and Extract Air Disc Valve SDV - B / EDV - B 100 80.0 l/s

Supply and Extract Air Disc Valve SDV - C / EDV - C 125 125.0 l/s

Supply and Extract Air Disc Valve SDV - D / EDV - D 160 180.0 l/s

Halcrow YollesPO Box 360 Dubai United Arab Emirates

Tel +971 43 3370380 Fax +971 43 3379239halcrowyolles.com

DESIGN BULLETIN

ISSUE DATE:

30th August 2007 SUBJECT:

Supply & Return Air DiffusersVOLUME DISC SERIES NO.

REVISION:

00 5 M 300 001

Supply and Extract Air Disc Valve SDV - E / EDV - E 200 230.0 l/s

Notes: The maximum recommended air flow is for guidance only. For each project the design mechanical

engineer to review the selection of size, based on location of diffuser and height of the false ceiling etc.

The above recommendations are based on achieving noise level of NC 30 in the occupied space. If specified noise levels are below NC 30, please check the Manufacturer’s ratings.

For special application, pl. review your selection with senior Mechanical Engineer. The supply air diffuser SD4 - X will be specified with opposed blade dampers and return air diffusers

will be without any damper. Try to avoid Square Diffuser neck size greater than 375 x 375 i.e. SD4-D. Try to avoid the use slot diffuser more than 4 slots. The sizes mentioned above are only for guidance and can be re-sized based on project

requirement. Diffusers for any other air flows to be selected based on manufacturer’s ratings.

Based on above, Schedule of Grilles & Diffuser will be prepared and Schedule will always be on Mechanical services Legend & Symbol Drawing.

The specifications will also refer to various references mentioned above. A change in specification will be carried out by the Sr. Mechanical Engineer.

Halcrow YollesPO Box 360 Dubai United Arab Emirates

Tel +971 43 3370380 Fax +971 43 3379239halcrowyolles.com

DESIGN BULLETIN

ISSUE DATE:

30th August 2007 SUBJECT:

Supply & Return Air DiffusersVOLUME DISC SERIES NO.

REVISION:

00 5 M 300 001

Issued By: Avinash P. JawharkarHead Of Mechanical Department

Halcrow YollesPO Box 360 Dubai United Arab Emirates

Tel +971 43 3370380 Fax +971 43 3379239halcrowyolles.com