Brochure

114
Selection Guides
Pressure and/or Temperature Pilot Operated Steam Regulators (continued)
Hoffman Specialty Series 2000 Regulator capacities, shown
in the flow capacity charts on pages 45 - 48 in the Series
2000 Ordering Information section, are based on test data.
The chart data indicates flow capacity values derived from
plots of test data that show the drop away (droop) from the
set pressure as shown in the graph below. The rated flow
capacity (A) is where the curve passes a pressure droop of
10% of set pressure below the set pressure (B) [i.e., 75 psi
x 0.1 = 7.5 psi (5.2 bar x 0.1 = .52 bar) below the set pres-
sure of 75 psig (5.2 bar)]. The curves in the graph below
demonstrate how the reduction in trim size affects perfor-
mance. As a general rule it is best to use the smallest valve
and trim possible that provides adequate flow capacity.
Accuracy of Control—Regulator Steam Capacities
Capacity units are not shown. Curves are typical for all Main Valve sizes.
A. Flow at which port will be rated 10% droop [i.e. 75 psig x .1 = 7.5 psig (5.2 bar x .1 = .52)] from set pressure.
B. Minimum controllable flow.
C. Pressure rise above set pressure upon closing.
Capacity vs Controlled Pressure for Typical Main Valve with Spring Pilot
Regulator saturated steam capacities are tabulated in
charts on pages near the Series 2000 Regulator Ordering
Information. Note that all valves are available in several
trim sizes to allow flexible selections. These capacities
have been determined as outlined in PTC 19.5; 4-1959
“Chapter 4 Flow Measurement, ASME Power test Code.”
The capacities conform to Fluid Controls Institute, Inc.
specification FCI-58-1, “Definitions of Regulator
Capacities.” The capacities are based on a 10% accuracy
of regulation [2 psig (.14 bar) minimum] with the set point
at minimum controllable flow, defined as 2% of maximum
flow. Capacities are the same for whichever pilot is uti-
lized.
When using the capacity tables remember:
• Values shown are maximum flow with minimum piping
restriction.
• Maximum single stage reduction 150 psi (10.3 bar)
(100 psi (6.9 bar) recommended).
• Values are for saturated steam; superheated steam
requires a correction factor.
• Outlet pressures lower than the lowest shown will have
a capacity equal to the lowest shown.
• All valves have 3 capacity ports available.
• Multi-stage reductions will have a flow capacity equal to
the lower flow capacity of the two.
psig
Controlled
Pressure
(bar)
85
80
75
70
65
60
55
50
(5.9)
(5.5)
(5.2)
(4.8)
(4.5)
(4.1)
(3.8)
(3.5)
Capacity A
Reduced Port
A
Normal Port
A
Full Port
A
Lock Up Pressure
C
B
Reduced Port
Normal Port
Full Port
Set Pressure = 75psig (5.2 bar)
Series 2000
Hoffman Specialty
®
Selection Guidelines