SCHMIDT® Flow Sensor SS 20.250

The smallest all-rounder – universal and powerful

Patented sensor head (dumb-bell head):

- Largely independent from flow direction

- Easy to clean (free of undercuts)

- Dirt-resistant

Flow and medium temperature signal
Probe length 300 … 500 mm
Measuring ranges 0 … 1 m/s to 0 … 20 m/s, special measuring range
Optional coated (not for Hygienic Design version)
Hygienic Design version optional

In many applications, the direct measurement of flow velocity or volume flow in air and gases is the ideal solution.

Due to high demands of modern control technology, the flow sensor has to detect precisely and fast an extremely wide measuring range from "almost zero" up to the maximum value.

For clean room applications also available as SS 20.250 Hygienic Design (order option):

Smooth surface (free of undercuts) prevents product or dirt residues
Corrosion resistant (stainless steel V4A)
Easy to clean
Resistant to all commercially available cleaning agents
Easy to remove for calibration due to plug-in connection

- Sensor with 1.5 m Hygienic Design cable and plug

- Additional 10 m Hygienic Design cable with socket included

Ventilation and air conditioning
Clean room and pharma
Monitoring of FFUs
Monitoring of laminar flow in cleanrooms

SCHMIDT Technology – simply a question of better measurement

Specifications

Technical data
Measuring quantity	Standard flow velocity w_N based on standard conditions ¹⁾ Temperature of medium T_M
Measured medium	Air or nitrogen, other gases upon request
Measuring range w_N	0 … 1 / 10 / 20 m/s; Special measuring range inbetween 1 … 20 m/s (steps of 0.1 m/s)
Lower detection limit w_N	0.06 m/s
Measuring range T_M	-20 … +70 °C
Measuring accuracy
Standard w_N	±(5 % of measured value + [0.4 % of fmr; min 0.02 m/s]) ²⁾
High precision (optional) w_N	±(3 % of measured value + [0.4 % of fmr; min 0.02 m/s]) ²⁾
Response time (t₉₀) w_N	3 s (jump from 0 to 5 m/s in air)
Temperature gradient w_N	< 2 K/min (at w_N = 5 m/s in air)
T_M (for w_N > 1 m/s)	±1 K (10 … 30 °C); ±2 K (remaining measuring range)
Operating temperature
Sensor / electronics	-20 … +70 °C
Storage temperature	-30 … +85 °C
General data
Humidity	Measuring mode: Non-condensing (< 95 % RH)
Operating pressure	Atmospheric (700 … 1,300 hPa)
Display	Dual-LED: - Green: Status - Red (flashing): Sensor defective
Supply voltage	24 V AC/DC ± 10 %
Current consumption	Typical < 60 mA, max. 100 mA
Analog outputs Type: Auto U / I)	w_N, T_M 0 … 10 V / 4 … 20 mA (switching of signal characteristic depends on R_L) -Voltage output (0 … 10 V): R_L ≥ 550 Ω (short-circuit protected) - Current output (4 … 20 mA): R_L ≤ 500 Ω - Change-over hysteresis: 50 Ω - C_L ≤ 10 nF Voltage output: RL ≥ 500 Ω Current output: RL ≤ 500 Ω Hysteresis: 50 Ω
Electrical connection	Non-detachable cable, 5 x 0,25 mm² Standard: Length 2 m or selectable (3 … 100 m; steps of 1 m), with ferrules Hygienic Design Option: 1.5 m, M12 plug (male, A-coded, 5 pole); Additional content of delivery: Cable 10 m, M12 bushing (female, A-coded, 5 pole)
Maximum cable length	Voltage interface / current interface: 100 m Voltage mode: Use AGND and R_L ≥ 10 k (mass offset)
Mounting position	Arbitrary
Minimum immersion depth	58 mm (< 58 mm upon request)
Protection type	IP65
Protection class	III (SELV or PELV)
Probe length	300/500 mm
Weight	200 g max.
Material
Sensor tube	Stainless steel 1.4571
Sensor head	PBT (glass-fibre reinforced), stainless steel 1.4571
Protective coating (optional)	Polyurethan / parylene (coating not available for Hygienic Design version)
Sensor cable	Standard: PUR, halogen-free Hygienic Design Option: PP-EPDM, halogen-free

¹⁾ Standard conditions: T_N = 20 °C and p_N = 1,013.25 hPa

²⁾ Related to adjustment reference; "fmr" = final measuring range

Subject to technical changes.

Order information

	Description	Article-Number
Basic sensor	SCHMIDT^® Flow Sensor SS 20.250; 2 x output signal 4 … 20 mA and 0 … 10 V; cable length 2 m	526 340-	X	Y	Z	P	A
	Options
Mechanical type	Sensor length 300 mm		1
Mechanical type	Sensor length 500 mm		2
Measuring range, adjustment accuracy and calibration	Mesuring range 0 … 1 m/s			1
	Mesuring range 0 … 10 m/s			2
	Mesuring range 0 … 20 m/s			3
	Special measuring range (1 … 20 m/s; 0.1 m/s)			9
	Standard adjustment				1
	Standard adjustment with factory calibration certificate				3
	High-precision flow adjustment, including factory calibration certificate				2
Protection type	Without protective coating					1
	With protactive coating (Polyurethan derivate black; sensor head only; not available for Hygienic Design version)					2
	With protactive coating (Parylene transparent; fully coated besides ca. 40 mm at the cable end; not available for Hygienic Design version)					3
Connecting cable	Cable length 2.0 m						1
	Special cable length: 3 ... 100 m; 1 m steps						2
	Hygienic design cable with fix linked to sensor 1.5 m, 5-pol M12 plug-in connector; additional content of delivery: 10 m hygienic design cable, 5-pol M12 bushing						3

Accessories

Connection technology

Description	Article-Number
Power supply unit: output 24 V / 1A DC, supply voltage 115/230 V AC (strip terminal)	535 282

Mounting and fixing technology

Description	Article-Number
Mounting flange, steel, galvanic zinc-plated	301 048
Wall-mounting flange, stainless steel, PTFE-clamping ring	520 181
Compression fitting, stainless steel, G½, atmospheric pressure	532 160
Compression fitting, brass, G½, atmospheric pressure	517 206
Welded sleeve, steel, G½, according to EN 10241, 5 pieces	524 916
Welded sleeve, stainless steel 1.4571, G½, according to EN 10241, 2 pieces	524 882
Adapter M18 x 1, G½	545 090
Assembly kit for pipe assembly suitable for MD 10.010/10.015, including pipe clamps and collar for adjustment for the pipe diameter	531 394

Measured value display

Description	Article-Number
SCHMIDT® LED display MD 10.010, in wall housing to show the volume flow velocity, 85 … 250 V AC and sensor power supply	527 320
SCHMIDT® LED display MD 10.010, similar to 527320 but with 24 V DC voltage supply	528 240
SCHMIDT® LED display MD 10.015, similar to 527320 but with additional sum function and second measuring input	527 330
SCHMIDT® LED display MD 10.015, similar to 527330 but with 24 V DC voltage supply	528 250

Miscellaneous

Description	Article-Number
Attachable protective clip for dumbbell head against mechanical influences, stainless steel	531 026
Attachable protective 2-wires-clip for protection against mechanical influences, stainless steel, H₂O₂-resistant	559 124