This document describes axial flow regulators, which are compact inline pressure regulators. They use an external pilot regulator to control the opening and closing of a rubber sleeve, which acts as both a diaphragm and valve. The main components are the axial flow valve, inspirator block, and ZSC100 pilot. The axial flow valve uses a simple rubber sleeve that opens and closes based on pressure differences. The inspirator block contains a Venturi that reduces control pressure as flow increases to open the sleeve. The ZSC100 pilot maintains a spring-loaded control pressure. Axial flow regulators are versatile and can be used for pressure reduction, flow control, and relief applications.

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Axial Flow Regulators

2. 2
Axial Flow Regulators
Compact in-line regulators that
sandwich between two flanges.
Capable of passing high volumes
of gas using external pilot
regulators to control the opening
and closing of a rubber sleeve.
The sleeve effectively acts as a
combined diaphragm and valve -
providing both sensing and
control.
The unit can be used as a
pressure regulator or relief valve.

3. 3
Axial Flow Regulators - Main Components
This diagram shows an
assembly of:
• Axial Flow Valve
• Inspirator Block &
• ZSC 100 Pilot
The following slides look at
these three items in turn.
An alternative Restrictor
Block is also available for
specialist industrial
applications where fast
response is required.

4. 4
Axial Flow Valve - Sub Components
The main regulator comprises a very simple set of components.
Upstream and downstream cages are interchangeable. This symmetry has the
result that the axial flow valve will control in both directions, although strictly the
fairing nut should be at the downstream side for flow smoothing.

5. 5
1. With gas supply pressure at
the back of the sleeve equal to
inlet pressure the sleeve is
closed against the inlet cage. A
closing force equal to inlet
pressure acts on the
downstream ‘V’ sleeve area
forcing it against the
downstream cage to give
double closure and completely
tight seal.
2. Reducing the pressure at the
back of the sleeve creates a
pressure imbalance across the
sleeve, inlet pressure now being
higher. This expands the sleeve
away from the cages thereby
allowing flow from inlet to outlet.
The pressure at the back of the
sleeve can now be referred to as
the ‘Control’ Pressure.
3. Reducing the control
pressure further increases the
differential across the sleeve
allowing it to expand further
until the sleeve is flat against
the body for 100% capacity.
The position of the sleeve and
therefore flow is controlled by
the pressure at the back of the
sleeve.
Axial Flow Valve - Operation

6. 6
Axial Flow Regulators - Inspirator Block
This block includes an
inspirator that acts in the
conventional manner.
The Venturi effect causes the
control pressure to reduce as
flow through the inspirator
increases. (It is this reduction in
control pressure that allows the
sleeve to “open”.)
The adjustable restrictor allows
regulator performance to be
tuned to improve control.

7. 7
Axial Flow Regulators - ZSC Pilot
The spring loaded pilot, shown
here, is spring biased open.
Note that the pilot does not load
the regulator but acts like an
auxiliary K regulator drawing
more flow through the inspirator
as demand increases.
The ZSC pilot is also available
as a relief valve, although for
this service must be reverse
acting e.g. spring biased closed.

8. 8
Axial Flow Regulators - Position Indicator

9. 9
Axial Flow Regulators - Configurations
Axial flow regulators are usually configured as monitor/active or two stage/monitor
override systems.
This diagram shows the latter two stage/monitor override arrangement, installed
with restrictor control rather than the more conventional inspirator.

10. 10
Key Advantages
 Very compact
 Greater capacity ‘size for
size’
 Simple in construction and
operation
 Reliable and easy to
maintain
 A wide range of application
using one common design
 A proven, low risk design
 Lower noise level

11. 11
Versatility
 Pressure reduction from 100 bar down to 30 mbar
 Active or monitor mode
 Two stage pressure cut
 Volumetric flow control
 Over and under pressure shut off
 Back pressure/relief valve
 Pulsating dampening
 Remote control via pneumatic or electronic signal
 Can be installed in any position
 Low operating differential

12. 12
P1
P1
Falling
Outlet
Pressure

13. 13
Quiet Axial Flow Regulator Components
Bolt Washer
Interchangeable
valve cage
closure Valve body Rubber sleeve
single working part
Interchangeable
valve cage
closure
Washer Fairing nut

14. 14
Pilots and Control Blocks
Restrictor Blocks
Inspirator Blocks
ZSC100 Pilot
1203EP Pilot

15. 15
Control Systems Differences
F F
P1 P2 P1 P2
PilotPilot
Inspirator
control
Restrictor
control
Restrictor