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WOOD FIBRE PADS vs. CELdek PADS |
WOOD FIBRE
|
CELdek
ALL
COOL BREEZE UNITS |
| ECOLOGY | |
| Wood fibre (wood wool) pads consist of cellulose wood fibre generally wrapped in a black plastic mesh. | CELdek pads consist of cellulose wood fibres in a paper form, treated with a small amount of chemicals to give it stiffness and long life. Adhesive is used to build its structure. |
| POROSITY | |
| Wood fibre pads have a wick like porosity, however this can only occur where strands of fibre cross and touch each other. This would be amply demonstrated if a wick test was carried out which would show that the rise of moisture is limited by the contact each strand has with one another. | CELdek pads have a wick like porosity. This is demonstrated by placing a piece of CELdek in 15mm of water, the porosity will be evident by the moisture seen climbing up the pad. |
| DUST FILTRATION | |
| Random material construction ensures airborne dust impinges on the filter material. Pads can sag over time, allowing airborne dust, insects and pollen to be carried through the system due to the gap formed at the top of the pad allowing air to take the path of least resistance. We have no knowledge of tests ever been carried out on wooden fibre pads. | Designed with self washing characteristics. A test carried out by Air Filter Laboratories in Louisville, Kentucky, USA performed according to the "Dust spot efficiency test ASHRAE STANDARD 52-76." The size and number of particles were measured with a laser counter up and down stream of the CELdek media. Please note that these tests were carried out on 7090 CELdek which has a smaller flute and hence would obtain a higher rating than CELdek pads with a larger flute size. |
| PRESSURE DROP | |
| In the manufacture of wood fibre pads it is very difficult to strike a uniform balance between the density of the pad and an acceptable pressure drop across the pad in order to maintain a high saturation efficiency. CSIRO tests in Australia show wood fibre pads packed to give above 80% saturation efficiency have a pressure drop 4 times higher than that of a CELdek pad at 1 m/s air velocity. | CELdek pads have a very low pressure drop when compared to wood fibre filter pads as clearly demonstrated by tests carried out by the Australian CSIRO. This means a smaller motor and cheaper running costs. |
| WATER APPLICATION AND CARRY OVER | |
| Limited amounts of water are generally applied to wood fibre pads to avoid the possibility of water carry over at relatively low pad face velocities of around 1 to 2 m/s. | CELdek pads can handle generous amounts of water that assist with it's self cleaning feature. CELdek pads do not suffer from water carryover whilst subjected to face velocities of up to 3 m/s. |
| CLOGGING OF PADS | |
| Wood fibre pads retain dirt and dust in the matrix which causes the pressure drop across the pad to increase relatively quickly. This closing down of the air movement causes the efficiency of the unit to fall and the running costs to rise. | CELdek pads self cleaning feature and low pressure drop allows the unit to run more efficiently for a much longer period, resulting in longer pad life and lower running costs. |
| PAD SAGGING | |
| Over time, wood fibre pads tend to sag. This may lead to the formation of gaps in or at the top of the pad itself. Gaps forming at the top of the pad may allow water from the water distribution system or manifold to be sucked directly into the unit. This frequently leads to the corrosion of unit casings and mechanical components. When this occurs, calcium and other dissolved solids build up on components as these stray water droplets evaporate. Lime and calcium deposits soon render a unit unserviceable. These gaps also lower the efficiency of the unit, which means that a unit is no longer capable of maintaining the low supply air temperatures for which it was designed. | CELdek pads are designed and built to be self supporting and do not sag. Better performance over the life of the pad is achieved. |
| PAD REPLACEMENT | |
| According to manufacture literature, wood fibre pads should be replaced every one to two seasons when pads become dust laden and the pores of the wood fibres become clogged. | CELdek pads last up to three times longer than wood fibre pads under the same conditions. |
| REPLACEMENT COST COMPARISON | |
| Australian figures show that although wood fibre pads are less expensive than CELdek pads of equal size, replacement costs exceed those of CELdek if taken over a period of 4 years. | Less frequent pad changes result in lower running expenses. CELdek pads are generally smaller than aspen pads when considering a given airflow. |
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