RHF FANS Ltd - Bifurcated Axial fans

INTRODUCTION

The RHF BIFURCATED FAN series is part of a comprehensive range of axial and centrifugal fan units, designed for application in the industrial fan market. As with all RHF fan products, particular attention has been paid to fundamental design concepts. These are allied to sophisticated production methods, which ensure that both optimum performance and cost effective products of the highest quality are guaranteed.

The RHF BIFURCATED FAN series consists of two casing types.

Both casing types ensure that the motor is isolated from the air stream. The motor sits within a tunnel, which passes all the way through the casing. This allows unrestricted air movement for motor cooling, which is of particular importance for higher temperature applications.

(1) BA-HD: - The middle section of the fan casing is enlarged to minimise the restriction of airflow. Coned ends have been carefully proportioned to give a smooth flow from the impellor barrel right through the casing. The use of a one piece spinning for the cone ends ensures accuracy and smooth aerodynamic transitions. These spun cone ends are made from a minimum of 3mm thick steel and are used on all sizes, regardless of whether the casing construction is in mild steel or stainless steel.

BA-HD TYPE FAN VIEW THROUGH TUNNEL BA-LD TYPE FAN

(2) BA-LD: - This particular fan consists of a cylindrical casing, which is less expensive than the HD type. The flow losses encountered with this design are naturally higher than those experienced with the HD type, due to greater restriction of free area. Notwithstanding the restriction, good performance can be achieved with a small penalty on absorbed power.

Standard Sizes

This catalogue contains the performance curves, performance tables and noise data based on aluminium impellors for the following sizes of fans. BA-HD 250,315,400,500,630,710 & 800 BA-LD 400,500,630,710 & 800 THESE FANS ARE STOCK ITEMS, AND CAN BE DESPATCHED WITHIN HOURS OF RECEIPT OF ORDER. Larger diameter fans can be offered to suit most reasonable delivery requirements.

Performance

Performance data has been obtained with tests carried out in accordance with BS848 Part 1and ISO 5801, Type ‘D’ full ducted installations. The motor ratings refer to the maximum output of the installed motor. When the impellor does not require the full power; the absorbed power will be less than the figures quoted.

Application

The RHF BIFURCATED FAN has been designed to handle both air and gas containing mists and dusts at normal and high temperatures. There is no detrimental effect on the motor, as it is isolated in a tunnel outside the air stream. It must be remembered to take account of abrasion or other damage to the impellor by abrasive materials. Where there is danger of vapour condensation or dust build up, the orientation of the HD type fan should not be horizontal, otherwise dust or condensation may build up in the middle section. Shaft seals are fitted to prevent the ingress of dust and minimise air or gas leakage into the motor tunnel. These seals are not gas tight and can be affected by condensation, corrosive chemicals or abrasive material. Please refer to RHF if special seals are required. The direction of airflow must be Form ‘B’.

Specifications

Fan Finish

Fan casings, mounting feet, matching flanges, guards and inlet bell mouths are hot dipped galvanised after manufacture. Alternatively, they can be supplied in a variety of powder coated or wet paint finishes. Stainless steel fan casings, impellors and ancillaries can also be supplied on short delivery times. These are glass bead blasted after manufacture to provide a consistent and clean dull finish.

Motors

Standard TEFC (IP55) flange mounted motors are used throughout the series. Single and three phase motors, Exna and Eexd Flameproof motors can be supplied, covering most international voltages at 50 or 60hz. Electrical connection is made directly to the motor terminal box, which is easily accessible within the motor tunnel.

Speed Control

Inverter drive speed control is available for all fan sizes, for both single phase and three phase supply.

Impellors

A comprehensive range of impellors is available, including: - (a) Fully adjustable aerofoil aluminium blades (b) Fully adjustable aerofoil Polypropylene blades (c) Fixed steel blade fabricated impellors The impellor blade angles are factory set to individual performance requirements.

Temperature application

All fans are suitable for operation up to 60° C. They can be fitted with a high temperature kit, which enables the fan to handle air or gas at 200° C, without any detrimental effect on the motor. This kit comprises of a special aluminium cooling impellor, mounted on the extended motor shaft to dissipate heat away from the motor shaft and bearings. The motor tunnel is lined on the inside with insulation material and protected by galvanised sheet. This ensures that the heat radiated onto the motor is kept to an absolute minimum.