Technical Data Moss Pressure Regulator : G417

The chart to the right shows the performance of the Moss Pressure Regulator.

The upper blue line (Unregulated) shows the pressure which would be applied to the fittings and tubing if no regulation took place.

The pink line shows the output pressure from the Moss Pressure Regulator.

As can be seen the Output Pressure is held to a constant 100 KPa with Input Pressures from 100 to 600 KPa. From 600 to 800 KPa the Output rises gradually to around 170 KPa. In most applications this is still acceptable. Over 800 KPa however, the Output Pressure becomes inconsistent.

The regulator works well when the water flow rate is between 1.8 and 11 litres per minute. If it exceeds 11 litre per minute, the output pressure will drop considerably because of the flow friction. Below 1.5 litre per minute the output pressure will tend to rise, the effect being more pronounced with higher input pressures.

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No water flows out

If no water flows out of the Regulator when connected to a tap, check to see that it has been installed in the correct direction. On the side of the Body is an arrow which indicates the direction the water must flow in order for the Regulator to work. Check that the water flow is correct. If not, simply undo the nuts and reverse the Regulator.

Excessive Noise

If the Input Pressure exceeds 600 KPa at a flow rate in excess of 11 litres per minute, a resonance can sometimes be set up, which causes the device to emit a high pitched noise. This noise can usually be eliminated by reducing the water flow rate through the Regulator.

One way to achieve this is to reduce the number of microsprays or drip emitters on the line. Split the line in to two sections for example. You can use In-line taps to control the flow to one line or the other.

Another way is to place an In-line tap before the G417 Regulator and turn it to a partially closed position, thus restricting the flow.

Leaking from the vent hole

On the side of the Moss pressure Regulator is a small hole, whose purpose is to allow air to escape from behind the sealing cup. There might be a small drip or dribble of water coming from this hole from time to time. If however it is a steady trickle or stream of water, it means that the seal is not holding.

Sometimes this is caused by the regulator being left off, in a dry condition for long periods of time in very hot sun. This can cause the seals to distort. Sometimes it is possible to fix this problem by applying water and turning the Regulator on and off over a few hours to get the seals to return to their original position.

If this doesn't work, you will have to replace the Regulator.

Excessive Pressure

As can be seen from the chart above, when the input pressure exceeds 600 KPa, the Output pressure will begin to rise above the regulated value of 100 KPa. If you have very high water pressure at the tap, this can be a problem.

One way which enables this problem to be overcome is to put two Regulators in series (that is, one behind the other on the same line.) The way this works is that the first Regulator reduces the pressure down to a manageable level (say 150 KPa), and the second Regulator then brings it down from 150 to 100KPa. In effect the pressure reduction is shared between the two Regulators. So, if you have very high water pressure, this is worth a try.