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Cranfield University test report

Cranfield University test report

Comparative performance study of

OC-1 Media and conventional sand filtration


Author: Prof. Hoi Yeung Mehrdad Silatani

Dept: Centre for Oil & Gas Engineering, School of Energy, Environment & Agrifood, Cranfield University

Report No: 15/HY/633

Date: September 2015




Executive Summary



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OC-1 Filtration Media.


The aim of the project has been defined to evaluate and investigate the performance of

a new filter media known as OC-1 Media against conventional sand filters used in

swimming pools.


Identical experimental rigs for sand and OC-1 Media filters were assembled for comparing the effectiveness and efficiency of the filters against one another.


OC-1 Media achieved the target NTU value by consuming considerably less energy while operating at lower pressure and constant flow-rate than sand filtration.


In conclusion, the OC-1 Media has been found to be as effective as sand filtration in

filtering swimming pool water whilst being more cost effective in terms of its power

consumption and more reliable in terms of its flow rate.



Test Set-Up

Photographs showing set-up layout

3D representation of the experimental setup

Piping layout and flow direction of each filtration system

Instrumentation and procedure

Power Consumption monitoring devices


Two identical power consumption meters were plugged into the mains upstream of the

adjustable speed pumps for monitoring the pump’s power usage.


Pressure Measurement


For monitoring pressure of the filtration system, a pressure gauge was installed on top of each filtration vessel. At the point of sampling water from each tank, pressure values of each tank were logged by using the installed pressure gauges.


Flow-rate Measurement


In-line floating flow meters were installed on the downstream line of the filters, which carry filtered water back to the water tank. Similar to pressure readings, flow-rate values were logged every time a water sample was taken to measure NTU values.


Test Results

Figures 10 and 11 represent the power consumption and system’s pressure respectively.

The increase in power consumption by sand filter can be attributed to the gradual increase in pump’s speed in order to maintain a constant flow-rate.



Figure 10

Figure 11

The main conclusions from conducted tests can be summarised as follows:


 • OC-1 Media proved to be as effective as traditional sand in reaching a target NTU value of 0.5.


 • OC-1 Media  has shown far greater capacity for filtering debris compared to traditional sand. In scenarios that cause the sand filter to block in seconds due to the heavy debris load, OC-1 Media continues to filter without a noticeable change in the system’s pressure or flow-rate. This signifies an advantage of OC-1 Media over sand as it requires backwashing less frequently.


 • In terms of power consumption, OC-1 Media consumes considerably less power for delivering the same filtration performance in comparison to traditional sand.


 • The OC-1 Media exhibited constant pressure and flow-rate throughout the testing period whereas traditional sand did not.


To sum up, by using OC-1 Media, one can expect a significant reduction in the power consumption of the system as well as greater capacity in filtering, while operating at a steady pressure and flow-rate.





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