| How should the by-pass be plumbed? |
| Each system is unique. To determine the best method of handling the by-pass in your system, you will need to review several factors: the liquid being pumped, how often you are in by-pass, the amount of flow being by-passed and the temperature of the pumped liquid. Generally, it is easiest and best to route the by-pass back to a properly baffled supply tank. The by-pass line should be connected to the opposite side of the tank from the feed line to the pump and separated by at least two baffles. If routing the by-pass back to the supply tank is not possible, then it may be routed to the inlet line to the pump. However, extra precautions should be taken. The by-pass line should be a reinforced, flexible hose one size larger than the pump inlet port and approximately 2-3 feet in length. This flexible hose absorbs pulsations and offers protection to the pump. A pressure reducing valve is recommended between the by-pass line connection and the pump inlet. The pumped liquid can quickly heat up when in by-pass. A thermal relief valve should be installed in the by-pass line for added protection. Heat build-up in the by-pass loop occurs much faster with high temperature liquids than with cold or ambient liquids. By-pass can also be directed to a floor drain.
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| Is there high pressure in the by-pass hose? |
| The by-pass line does not see high pressure, however, the pressure may be higher than the inlet pressure rating of your pump, so it is a consideration when designing the system. There are three main factors that govern the pressure in the by-pass mode. 1] the internal restriction of flow within the unloader, 2] the amount of flow from the pump, 3] the length and diameter of the by-pass line.
It is generally recommended to use a flexibly, reinforced hose rated to 200 PSI to allow for small pressure increases or spikes in the by-pass line. When routing the by-pass back to the inlet of the pump, it is recommended to install a pressure reducing valve between the by-pass line connection and the pump inlet to assure you are within the pressure limits of the pump.
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