Installation and Operation Manual
Urano - Pressure Regulating Valve MI-31
Elaborado Verificado / Aprovado CSQ Data Revisão Página
JJ JJ JM 05/07/21 05 4 de 74
All regulators, shutoff valves, relief valves, etc., must be installed with the correct flow direction.
Impulse lines are important components of any control system, and their proper installation is essential, with
no isolation valves.
Impulse lines shall be properly supported to reduce excessive vibration, which may cause fatigue rupture.
They shall also be positioned so that they cannot serve as hand or footrest. Impulse lines should be slightly
inclined so that liquid and condensates drain towards the main pipe.
When necessary (in underground facilities or indoor area) a ventilation pipe shall be installed from the
threaded hole (ؼ” NPT), found in the valve bell or in the diaphragm housing, and extended to a safe and
ventilated location, with the vent output protected to prevent it from inlet of rain water and insects that can
obstruct ventilation.
Auxiliary systems shall not be changed or modified without knowledge of the operating conditions and
the responsible personnel permission.
1.2.3 OPERATION
Depending on the regulator type, its valve may be positioned fully open. Consequently, when putting a
regulator in operation the shutoff valves shall be opened slowly, so that the regulator valve can assume its
regulating position. If the shutoff valves are quickly opened, the upstream pressure can pass through the
regulator and over-pressurize the downstream section of the main line.
All regulators, etc. shall operate with the regulation spring specified by the manufacturer. This is particularly
important when operating relief valves or shutoff valves, since incorrect springs may prevent a relief valve to
open and a shutoff valve to close.
Precautions shall be taken to prevent water inlet through breathing and ventilation openings.
1.2.4 MAINTENANCE
Regulators and valves contain gases under pressure, sometimes at a much higher pressure than the
atmospheric pressure. Before attempting to investigate a problem, or perform maintenance work on an
equipment, it must be safely depressurized. Furthermore, as many gases may be flammable, toxic,
corrosive, or hazardous, it may be necessary to purge the system with an inert gas, such as nitrogen.
Special precautions are required for operation with gases such as oxygen or hydrogen chloride, and the user
must ensure that proper procedures are implemented.
Eventually, it is not enough to isolate the high-pressure device, since high pressure can be retained
downstream of the isolation valves. Do not try to remove caps, plugs, etc, before the device is properly
released. Even so, it is wise to consider that high-pressure gas may be trapped when removing covers and
plugs.
Most regulators use spiral springs as the charging device. It is important to reduce these springs loading by
moving their pressing plates backwards as much as possible. In some cases, the spring may contain some
residual load, even when it is relaxed to the limits of its housing.
