Soft-start valves and soft-start units for compressed air
A soft-start valve fills a machine or a branch of the air line gradually through a throttle orifice after the compressed air is switched on. When the pressure after it reaches roughly half the inlet pressure, it releases the full flow. Meanwhile, the cylinders move into their initial position slowly and without jolts.
Among the air treatment units, soft-start valves are part of the modular FUTURA range for potentially explosive atmospheres, in four sizes with G 1/4" to 1" threads. Besides the soft-start valve itself, there are soft-start units that start the filling with a coil or with pilot air.
Soft-start valves and units by actuation
“Inlet up to” is the highest air line pressure the version withstands; the lowest is 2.5 bar for all. The soft-start valve without a coil is controlled by the incoming air itself: it starts filling as soon as you let the air in. The air-operated unit waits for pilot air at the G 1/8" port. The flow applies to the largest size.
| FUTURA soft-start valves and soft-start units — version comparison | |||||
|---|---|---|---|---|---|
| Version | Connection | Inlet up to | Coil voltage | Flow up to | ATEX |
| Soft-start valve BF…-F | G 1/4"–1" | 12 / 16 bar | no coil | 10,000 l/min | some versions |
| Soft-start unit with coil BFMCL… | G 1/4"–1" | 10 bar | 24 V DC, 24 V AC, 115 V AC, 230 V AC | 8,750 l/min | – |
| Air-operated soft-start unit BFPCL… | G 1/4"–1" | 12 / 16 bar | air-operated | 8,750 l/min | some versions |
Size 0 withstands an inlet of 12 bar at most. The 24 V AC voltage is only for the soft-start unit with a G 3/4" thread. Neither size 0 nor soft-start units with coil are for use in potentially explosive atmospheres.
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How the soft-start valve works
After switching on, the air flows through a throttle orifice and the pressure after the valve rises gradually. When it reaches roughly half the inlet pressure, the valve switches to full flow.
You set the filling time with the adjusting screw: turning it clockwise lengthens it, anticlockwise shortens it.
Without a soft-start valve, the machine is pressurised all at once after start-up, and cylinders that are not in their end position can move out abruptly. The soft-start valve thus protects both the operator and the machine.
Soft-start valve or soft-start unit
Soft-start valve
Starts filling as soon as air reaches it. You let air into the machine with a shut-off valve before it. Inlet 2.5–16 bar.
Soft-start unit with coil
A soft-start valve and a 3/2 valve in one block. You switch the filling on with a 24 V DC, 115 V AC or 230 V AC coil, for example from the machine control. Inlet 2.5–10 bar.
Air-operated soft-start unit
The same unit without a coil. Filling is started by pilot air applied to the G 1/8" port. Inlet 2.5–16 bar.
Where to place the soft-start valve
The soft-start valve goes before the filter, regulator and lubricator. At the very start of the unit, before the soft-start valve, put a shut-off valve with exhaust, with which you shut off the machine during maintenance and lock it with a padlock.
Mount the valve in the direction of the arrow on the body. You connect it to other components of the same size with a connection kit regardless of the thread, and to a wall with a mounting bracket. You will find mounting brackets, connection kits and the spare pilot valve with coil, which is the same for all sizes of soft-start units, among the spare parts and accessories.
Potentially explosive atmospheres
Soft-start valves and air-operated soft-start units in sizes 1, 2 and 4 are mechanical devices with no ignition source of their own. According to the declaration regarding Directive 2014/34/EU, you can use them in zones 1 and 2 (gases IIA, IIB, IIC) and 21 and 22 (dust IIIA, IIIB), temperature class T4, under the conditions described for the entire FUTURA range.
Soft-start units with coil, whose pilot valve would need its own design for explosive atmospheres, are not for use in potentially explosive atmospheres. Nor is any size 0 version.
Where to go next
| Related pages | |
|---|---|
| Where next | What you will find there |
| FUTURA soft-start and check valves | Flows and dimensions by size, order numbers of soft-start valves and units, mounting. |
| Switching valves for air treatment units | 3/2 valves that switch the air on and exhaust the outlet, operated by a coil or by air. |
| Check valves for air treatment units | Let air through only in the direction of the arrow, with side ports before the valve. |
| Manifold modules for air treatment units | Air branches from the unit to several points, on FUTURA also with a pressure switch. |
| Complete air treatment units | Filter, regulator and lubricator in one assembly. |
Ventilek’s tip
First shut off, then let the air in gradually. Put a ball valve with exhaust before the soft-start valve. During maintenance you shut off and lock the machine; after opening, the soft-start valve pressurises it without jolts.
- What is a soft-start valve for?
- After the air is switched on, it fills a machine or a branch of the air line gradually. The cylinders move into their initial position slowly and do not move out abruptly.
- When does the soft-start valve switch to full flow?
- When the pressure after it reaches roughly half the inlet pressure.
- How do I set the filling time?
- With the adjusting screw: clockwise lengthens the filling, anticlockwise shortens it.
- What is the difference between a soft-start valve and a soft-start unit?
- The soft-start valve starts filling as soon as air arrives. The soft-start unit also has a 3/2 valve, so you switch the filling on with a coil or with pilot air.
- What pressure does the soft-start valve need?
- At least 2.5 bar at the inlet. The soft-start unit with coil works up to 10 bar, the others up to 16 bar, size 0 up to 12 bar.
- Is it suitable for potentially explosive atmospheres?
- Soft-start valves and air-operated soft-start units in sizes 1, 2 and 4 are, according to the declaration regarding Directive 2014/34/EU. Soft-start units with coil and size 0 are not.
Product sorting
List of products
Soft-start valve FUTURA BF12-F, size 2: G 1/2" thread, flow 4,500 l/min, inlet pressure up to 16 bar, for ATEX environments.
Soft-start valve FUTURA BF382-F, size 2: G 3/8" thread, flow 4,500 l/min, inlet pressure up to 16 bar, for ATEX environments.
Soft-start valve FUTURA BF14-F, size 1: G 1/4" thread, flow 2,000 l/min, inlet pressure up to 16 bar, for ATEX environments.
Soft-start valve FUTURA BF38-F, size 1: G 3/8" thread, flow 2,000 l/min, inlet pressure up to 16 bar, for ATEX environments.
Soft-start unit FUTURA BFMCL382-230VAC, size 2: G 3/8" thread, flow 3,400 l/min, 230 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL382-24VDC, size 2: G 3/8" thread, flow 3,400 l/min, 24 V DC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL12-230VAC, size 2: G 1/2" thread, flow 3,400 l/min, 230 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL12-24VDC, size 2: G 1/2" thread, flow 3,400 l/min, 24 V DC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL14-230VAC, size 1: G 1/4" thread, flow 1,300 l/min, 230 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL14-24VDC, size 1: G 1/4" thread, flow 1,300 l/min, 24 V DC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL38-230VAC, size 1: G 3/8" thread, flow 1,300 l/min, 230 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL38-24VDC, size 1: G 3/8" thread, flow 1,300 l/min, 24 V DC coil, inlet pressure up to 10 bar.
Soft-start valve FUTURA BF10-F, size 4: G 1" thread, flow 10,000 l/min, inlet pressure up to 16 bar, for ATEX environments.
Air-operated soft-start unit FUTURA BFPCL014, size 0: G 1/4" thread, flow 1,300 l/min, inlet pressure up to 12 bar.
Air-operated soft-start unit FUTURA BFPCL10, size 4: G 1" thread, flow 8,750 l/min, inlet pressure up to 16 bar, for ATEX environments.
Air-operated soft-start unit FUTURA BFPCL12, size 2: G 1/2" thread, flow 3,400 l/min, inlet pressure up to 16 bar, for ATEX environments.
Air-operated soft-start unit FUTURA BFPCL14, size 1: G 1/4" thread, flow 1,300 l/min, inlet pressure up to 16 bar, for ATEX environments.
Air-operated soft-start unit FUTURA BFPCL34, size 4: G 3/4" thread, flow 8,750 l/min, inlet pressure up to 16 bar, for ATEX environments.
Air-operated soft-start unit FUTURA BFPCL38, size 1: G 3/8" thread, flow 1,300 l/min, inlet pressure up to 16 bar, for ATEX environments.
Air-operated soft-start unit FUTURA BFPCL382, size 2: G 3/8" thread, flow 3,400 l/min, inlet pressure up to 16 bar, for ATEX environments.
Soft-start unit FUTURA BFMCL014-230VAC, size 0: G 1/4" thread, flow 1,300 l/min, 230 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL014-24VDC, size 0: G 1/4" thread, flow 1,300 l/min, 24 V DC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL10-230VAC, size 4: G 1" thread, flow 8,750 l/min, 230 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL10-24VDC, size 4: G 1" thread, flow 8,750 l/min, 24 V DC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL12-115VAC, size 2: G 1/2" thread, flow 3,400 l/min, 115 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL34-230VAC, size 4: G 3/4" thread, flow 8,750 l/min, 230 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL34-24VAC, size 4: G 3/4" thread, flow 8,750 l/min, 24 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL34-24VDC, size 4: G 3/4" thread, flow 8,750 l/min, 24 V DC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL38-115VAC, size 1: G 3/8" thread, flow 1,300 l/min, 115 V AC coil, inlet pressure up to 10 bar.
Soft-start valve FUTURA BF014-F, size 0: G 1/4" thread, flow 2,000 l/min, inlet pressure up to 12 bar.
Soft-start valve FUTURA BF34-F, size 4: G 3/4" thread, flow 10,000 l/min, inlet pressure up to 16 bar, for ATEX environments.
Soft-start unit FUTURA BFMCL014-115VAC, size 0: G 1/4" thread, flow 1,300 l/min, 115 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL10-115VAC, size 4: G 1" thread, flow 8,750 l/min, 115 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL14-115VAC, size 1: G 1/4" thread, flow 1,300 l/min, 115 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL34-115VAC, size 4: G 3/4" thread, flow 8,750 l/min, 115 V AC coil, inlet pressure up to 10 bar.
Soft-start unit FUTURA BFMCL382-115VAC, size 2: G 3/8" thread, flow 3,400 l/min, 115 V AC coil, inlet pressure up to 10 bar.