PN16
BURKERT 20060708 (Type 6757) is a direct-acting, media-separated 2/2-way Whisper flipper solenoid valve configured in Circuit Function B (normally open). Built with an 18 mm body width, high-performance PEEK housing, and perfluoroelastomer (FFKM) seals, it is engineered for critical fluid control in medical technology, in-vitro diagnostics (IVD), environmental analysis, and laboratory dosing systems. The valve combines a nominal diameter of DN 2.0 mm with vacuum to 10 bar operating pressure capability, offering rapid switching times of approximately 7 ms and acoustic switching emissions below 45 dB(A).
Design and Operating Principle
Type 6757 utilizes a direct-acting flipper switching mechanism isolated from the fluid path by an elastomer separating diaphragm. Fluid media contacts only the PEEK valve body and FFKM seals, protecting internal electromagnetic components from corrosion and preventing thermal transfer from the coil into sensitive working fluids.
Key design attributes supported by the manufacturer documentation:
- Low switching noise: Acoustic emission remains below 45 dB(A) when measured in a sound measurement chamber according to ISO 3745 accuracy class 1.
- Fast cycle response: Opening time is approximately 7 ms (0% to 10% pressure build-up) and closing time is approximately 7 ms (100% to 90% pressure reduction), measured at +20 °C according to DIN ISO 12238:2001.
- High back-pressure sealing: Direct flipper design ensures reliable seal integrity up to the full rated differential pressure of 10 bar.
- Rinse and cleaning compatibility: Withstands hot cleaning cycles up to +90 °C for a maximum duration of 30 minutes.
- Service life: Rated for 10 million switching cycles based on laboratory endurance tests.
Technical Data
| Parameter | Technical Specification |
|---|---|
| Circuit Function | 2/2-way solenoid valve, normally open (CF B / WW B) |
| Actuator Type | Direct-acting flipper mechanism |
| Orifice Size (DN) | 2.0 mm |
| Pressure Range | -1.0 bar to 10.0 bar (Vacuum to 10 bar) |
| Max. Differential Pressure | 10.0 bar |
| Nominal Voltage | 24 V DC |
| Voltage Tolerance | ±5% (including residual ripple) |
| Power Consumption | 4.5 W |
| Flow Value Kv (Water) | 0.080 m³/h (measured at +20 °C, 1 bar inlet, free outlet) |
| Flow Value Cv (Water) | 0.092 gpm |
| Nominal Flow QNn (Air) | 86 l/min |
| Switching Time | Open: ~7 ms / Close: ~7 ms |
| Switching Noise | < 45 dB(A) |
| Fluidic Body Material | PEEK (Polyetheretherketone) |
| Seal Material | FFKM (Perfluoroelastomer rubber) |
| Medium Temperature | +15 °C to +50 °C (cleaning cycles up to +90 °C, max. 30 min) |
| Ambient Temperature | +15 °C to +50 °C |
| Storage Temperature | -10 °C to +65 °C |
| Maximum Viscosity | 21 mm²/s |
| Port Connection | Bürkert sub-base flange (18 x 69 mm, Version B1) |
| Electrical Connection | Rectangular plug grid 5.08 mm (Type 2505 compatible) |
| Degree of Protection | IP30 according to EN 60529 |
| Protection Class | Class III according to IEC 61140 / NEC Class II Power Supply |
Cleaning Cycle Conditions
The maximum valve body temperature must not exceed +110 °C. The valve must not be cycled during the +90 °C flushing procedure. Ensure adequate convective heat dissipation across the metallic surfaces during continuous operation.
Materials and Chemical Resistance
| Item No. | Component | Material | Wetted |
|---|---|---|---|
| 1 | Cover | Polyamide (PA) | No |
| 2 | Coil housing | Nickel-plated brass / steel | No |
| 3 | Valve housing | Polyphenylene sulfide (PPS) | No |
| 4 | Separating diaphragm | Perfluoroelastomer rubber (FFKM) | Yes |
| 5 | Valve body | Polyetheretherketone (PEEK) | Yes |
| 6 | Sub-base seal | Perfluoroelastomer rubber (FFKM) | Yes |
| 7 | Oval head screws | Stainless steel | No |
Wetted surfaces are restricted entirely to PEEK and FFKM, providing high chemical resistance against aggressive acids, bases, and organic solvents. Media compatibility can be verified using the Bürkert resistApp chemical resistance chart.
Fluidic Connections and Circuit Function B
BURKERT 20060708 operates under Circuit Function B (normally open). In the de-energized state, the flow path between the normally open port (NO) and the common working port (COM) remains open. Energizing the coil shifts the flipper to seal the orifice seat, cutting off fluid transmission.
| Circuit Function | DN | NO Port Pressure | COM Port Pressure | Dummy Port | Max. Differential Pressure | Prescribed Flow Direction |
|---|---|---|---|---|---|---|
| CF B (2/2-way NO) | 2.0 mm | Vac to 10 bar | Vac to 10 bar | Blanked / Inactive | 10 bar | NO → COM |
Flow Direction and Pressure Limits
In vacuum operation and standard pressurized service, observe the prescribed flow direction from NO to COM. For incompressible media, line pressure surges (water hammer) must not exceed the maximum permissible differential pressure of 10 bar.
Dimensions and Flange Pattern
The sub-base configuration measures 18 mm in width with a 69 mm body pitch. Fastening is accomplished using two metric M4 x 10 stainless steel screws included in the scope of delivery.
Mounting Instructions
- Installation orientation is optional, preferably with the actuator upright.
- Clean all interconnecting pipelines and sub-base manifold surfaces before installation.
- Install a dirt trap or inline filter with a recommended mesh width of 5 µm upstream of the valve inlet.
- Ensure manifold surfaces are flat and exhibit sufficient surface finish to prevent seal extrusion.
- Verify that the FFKM sub-base O-ring seal seats properly in the valve body recess.
- Tighten metric screws into metal manifold threads to a tightening torque of 1.5 Nm.
Block Installation and Operating Restrictions
When multiple Type 6757 valves are mounted side-by-side on a shared manifold block, thermal coupling limits the continuous operating envelope and pressure rating.
| Configuration | Orifice (DN) | Circuit Function | Area P1 (NO Port) | Area P2 (NO Port) | Duty Cycle Limit |
|---|---|---|---|---|---|
| Single Installation | 2.0 mm | CF B | Vac to 10 bar | - | 100% ED continuous |
| Block Structure (22 mm pitch) | 2.0 mm | CF B | Vac to 10 bar | - | 50% ED continuous |
| Block Structure (20 mm pitch) | 2.0 mm | CF B | - | Vac to 9 bar | 80% ED continuous |
| Block Structure General | 2.0 mm | CF B | - | - | 70% ED (max. 10 min duty cycle) |
- The minimum permitted width per station in block installation is 18.5 mm.
- The maximum valve metal housing temperature must remain below +110 °C under all operational circumstances.
Electrical Installation
Type 6757 requires a regulated 24 V DC supply voltage with a maximum voltage tolerance of ±5% (inclusive of residual ripple).
Electrical Polarity and Supply Quality
Correct electrical polarity is a mandatory prerequisite for proper switching operation. Do not operate the valve with unsmoothed, rectified alternating current. Ensure compliance with Protection Class III / NEC Class II power supply limits.
The valve features an integrated 2-pin terminal interface (pitch 5.08 mm) designed to accept Type 2505 rectangular cable plugs. Push-in cable connectors are not included with the bare valve and must be ordered separately.
Maintenance and Troubleshooting
Type 6757 is largely maintenance-free under normal operating conditions. Regular inspections should check for:
- External medium leakage around the flange seal and diaphragm area.
- Proper operating pressure within the rated vacuum to 10 bar range.
- Correct supply voltage (24 V DC ±5%) and electrical polarity.
- Fluidic port assignment according to Circuit Function B (Port 1 / NO to COM).
Compatible Accessories
Type 2505 cable plugs provide the required IP30 electrical connection:
| Accessory Description | Configuration | Cable Length | Order Article No. |
|---|---|---|---|
| Cable plug 10 mm, 2-pin (Type 2505) | Straight | 0.3 m | 644068 |
| Cable plug 10 mm, 2-pin (Type 2505) | Straight | 0.6 m | 162144 |
| Cable plug 10 mm, 2-pin (Type 2505) | Straight | 3.0 m | 252572 |
| Cable plug 10 mm, 2-pin (Type 2505) | Straight | 5.0 m | 255194 |
| Cable plug 10 mm, 2-pin (Type 2505) | Angled | 3.0 m | 381035 |
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