Because it needs no plumbing and it stays with the station it belongs to.

An in-line regulator has to be mounted somewhere, plumbed into the working line, and supported. On a machine with limited space that means finding a location, and wherever it ends up it is physically separated from the valve that drives the cylinder - so the relationship between them is not obvious to anyone maintaining the machine later.

A sandwich regulator occupies the interface that already exists between the valve and its base. It adds its own thickness to the stack and nothing else: no brackets, no additional fittings, no extra tube.

It is also unmistakably associated with that station, so a technician looking at the terminal can see immediately which valve is regulated and to what pressure.

On a valve terminal the argument is stronger still, because an in-line regulator would break the consolidation the terminal was chosen for.

Whenever an actuator needs less force than the system pressure would give it - which is more often than people expect.

The usual cases are delicate handling: a gripper on fragile product, a clamp on a soft or thin-walled component, a locating pin that should position rather than deform.

Ejection and blow-off are another: at full system pressure an ejector can fire product across the machine, and a blow-off nozzle uses far more air than the job requires.

Safety is a third. Reducing the force available at a particular actuator can be part of reducing the risk it presents, particularly where an operator works nearby - though it is a risk-reduction measure rather than a safety function in itself.

And energy: an actuator running at higher pressure than it needs consumes more air every cycle, so regulating stations down where possible reduces consumption across the machine's life.

Yes - dual regulators handle each outlet independently, which is exactly what many applications need.

A double-acting cylinder frequently needs different forces in each direction. A press or clamp needs full force on the working stroke and very little to return. A vertical cylinder needs more pressure to lift than to lower, since gravity assists one direction.

A dual sandwich regulator provides a separate setting for each outlet port, so both can be tuned independently.

The benefit beyond force control is air consumption. Setting the return stroke to the minimum pressure that reliably returns the cylinder can save a substantial proportion of that cylinder's air, and across a machine with many actuators that adds up.

Single-outlet versions regulate only one port, which suits a single-acting cylinder or a case where only one direction matters.

Specify which - the two look similar and are not interchangeable in effect.

By a screw or knob on the regulator body, usually with a locking arrangement to prevent unintended change.

Adjustment is the same in principle as any regulator: turning the adjuster changes the spring loading on the regulating element and therefore the outlet pressure. A gauge, either fitted to the regulator or connected temporarily, is needed to set it accurately.

Because a sandwich regulator sits in a stack of similar-looking modules, the setting is easy to disturb accidentally - so most have a push-lock or lockable adjuster that must be deliberately released.

The practical point is to record the intended setting. A regulator whose pressure has been altered produces a machine that clamps too lightly or too firmly, and unless the correct value is documented there is nothing to restore it to.

Mark the station and its intended pressure on the machine documentation alongside the valve terminal's station schedule.

No - it is specific to the valve range and mounting interface, since it has to sit in that interface.

A sandwich regulator reproduces the valve's mounting footprint on both faces: it presents the manifold's interface upward to the valve, and the valve's interface downward to the manifold. That geometry is specific to the range.

So it must be ordered for the particular valve family and size, and cannot be transferred between makes or between different series from the same maker.

It also adds height to the stack, which matters where space above the manifold is limited or where a cover has to fit over the assembly - worth checking before ordering rather than after.

On a valve terminal, confirm that the range supports sandwich modules at all and at which stations, since some compact terminals do not accommodate them.

Record the part number with the station schedule so a replacement can be ordered without dismantling anything.

Somewhat less than the valve it serves, because the air passes through the regulating element - and it should be checked against the actuator's requirement.

Adding any regulator to a line introduces a restriction. The regulating element and its seat are a flow path narrower than a straight passage, so the assembly's flow capacity is lower than the valve alone would deliver.

On a small actuator that is irrelevant. On a large cylinder needing rapid movement, the regulator can become the restriction and the cylinder becomes noticeably slower once it is fitted - which is often misdiagnosed as a valve or cylinder problem.

So check the regulator's flow figures at the intended outlet pressure against the actuator's demand, remembering that flow capacity falls as the pressure drop across the regulator increases.

Where both a large flow and a reduced pressure are needed, an in-line regulator sized for the flow may be the better answer despite the plumbing.

The same interface accepts other functions - flow controls, check valves, pressure switches and blocking modules - which is a broader capability worth knowing about.

Because the mounting interface is standardised within a range, manufacturers offer a family of modules that stack in it. Sandwich flow controls meter the exhaust to set cylinder speed at the station rather than at the cylinder. Sandwich check valves hold a cylinder position if pressure is lost. Pressure switches sense the station's pressure and report it.

Blocking or isolation modules allow a single station to be shut off independently, which addresses the difficulty that a terminal shares one supply.

So the interface becomes a place to add functions without adding plumbing, and several modules can be stacked at one station if the height allows.

When designing a terminal, it is worth reviewing what modules the range offers - functions that would otherwise need separate components in the tubing can frequently be brought into the block.