W4 MKII Filterability Apparatus


W4 MKII Filterability Apparatus

The Armfield Filterability Apparatus enables a water quality test to be made on a suspension to be filtered through sand or similar granular media. As well as for student teaching, it can be used in routine control at waterworks, or at a sewage treatment works that employs teriary filtration.


The Filterability Apparatus utilises a bed of granular material, which can be chosen by the investigator to suit their own purposes.

The measurements taken with this apparatus enable a filterability number to be calculated, which has significance in deep-bed filter performance. For example, the effects of changing pre-treatment dosing can be evaluated before making changes on the operating plant.

Solenoid valves enables the operator to select the direction of flow through the granular bed. At the base of the column is a sieve mesh to retain the granular media. Wastewater can either flow downward via gravity from the funnel into the column to demonstrate filterability or via a pump to demonstrate head loss characteristics using an electronic pressure sensor. The new W4-MKII also enables backwashing of the granular bed using the pump. All tubing connections are transparent to enable operations to be observed and air bubbles avoided.

Technical Specifications

Sample tube I/D: 0.038mm

Sample tube length: 0.60mm

Pump operating range: 0-100 L/hr

Solenoid valves: 1

Differential pressure sensor: 0-1 psi

Features & Benefits

  • Metal framework with transparent test section for observation
  • Electronic control and data logging via PC
  • Self-contained
  • Pump to enable constant flowrate and backwashing
  • Operational manual with teaching exercises
  • Universal single wire interface for control and data logging
  • Digital timer
  • Thermometer
  • 1L glass beaker


Triple beam balance with 0.1g sensitivity (Ordering code: INST059)

  • Equipment consists of a metal framework supporting a 1.5L vessel connected by transparent tubing to a 60mm-high test filter cell
  • Peristaltic pump
  • Electronic Pressure Sensor
  • 1L collecting beaker
  • Digital LCD timer
  • Thermometer
  • Solenoid Valve
  • Software for control and data logging
  • Results viewer software for analysing data
  • Operational manual with teaching exercises

Electrical supply: supplied with a universal mains adaptor suitable for 100-240V / 1ph / 50-60Hz

Software requires a computer running Windows XP or above with a USB port (computer not supplied by Armfield)

Packed and crated shipping specifications

Volume: 1.5m³
Gross weight: 15Kg

Length: 0.43m
Width: 0.38m
Height: 0.97m

  • W4-MkII
  • INST059 (optional)