Installation Manual, Maintenance and Operation
Pressure Regulating Valve – Model Horus
MI-18
J.Junior Celso Nieto JM 25/11/16
04 7 de 32
PILOT G-42
SPRING COLOR CODE ADJUSTMENT RANGE
GREEN 01.49.65 1,0 – 4,5 bar
GRAY 01.49.64 4,5 – 12,0 bar
BLUE 01.49.33 11,0 – 17,0 bar
RED 01.51.94A 16,0 – 30,0 bar
YELLOW 01.51.94 27,0 – 55,0 bar
2.3.8 ACCURACY AND LOCK UP
Accuracy; Closing: AC up to 1; SG up to 2,5
3.0 – PRINCIPLE OF OPERATION
3.1 REGULATOR SPRING TO CLOSE (FC)
During pressure absence, shutter (A) is kept in closed position by the shutting spring (B), which keeps it pressed
against the gasket (C). It stands out that even when subject to pressure, upstream pressure variations have no influence
on the shutter position, due to the balancing of the forces acting on the same, as well as on the actuator shaft (D) that is
also balanced.
When the inlet piping is pressurized, gas reaches the booster (F), which reduces the pressure to a convenient value
near to the outlet pressure and delivers the same to pilot (G). The pilot compares the gas feeding pressure with the outlet
pressure, sensed by the pilot diaphragm (H), and controls the flow to be injected under the main regulator diaphragm (L).
If a decrease in downstream pressure occurs (due to an increased consumption or a drop of the upstream pressure)
an imbalance between the spring (I) force on the pilot (H) diaphragm and the force generated by the outlet pressure under
this same diaphragm, drives the pilot (K) shutter to a larger aperture, therefore, causing a pressure increase under the
main regulator (L) diaphragm, which combined with downstream pressure drop, which actuates on the main regulator
diaphragm and in the opposite side of the pilot pressure thereon, will determines the displacement of the shutter (A)
upwards, thereby increasing the passage and restoring the set point.
When the pre-regulated pressure begins to increase, it makes the pilot (K) shutter to reduce the aperture. The
increased pressure, which actuated under the regulator (L) diaphragm, flows through the Bleed (M) restriction (adjustable)
that discharges the same downstream. The strength of the closing spring of the main regulator (B) plus the decrease of the
pilot pressure cause a downward displacement of the main shutter (A), making the pressure to return to the preset value.
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