SCHMIDT® Flow Switch SS 20.200

Thermal Flow Switch for monitoring of flow rate of air and gases.

Patented sensor head (dumb-bell head):

- Largely independent from flow direction

- Easy to clean (free of undercuts)

- Dirt-resistant

Probe length 100 … 500 mm
Measuring ranges 0 … 1 m/s to 0 … 20 m/s
Visual indication of switching and operating status
Potentiometer (pre-programmed as option)
Increased resistance to media with optional coating

Exhaust air monitoring system
Filter monitoring
Fume cupboards
Clean room and Pharma
Ventilation and Air conditioning
Semiconductor process equipment

SCHMIDT Technology – Simply a question of better measurement

Specifications

Technical data
Measuring quantity	Standard flow velocity w_N based on standard conditions ¹⁾
Measured medium	Air or nitrogen, other gases on request
Measuring range w_N	0 … 1 / 2.5 / 10 / 20 m/s
Lower detection limit w_N	0.06 m/s
Threshold w_N	5 … 95 % of measurement range (min. 0.1 m/s)
Threshold setting w_N	Potentiometer (270°)>br>Optionally pre-programmed by factory (potentiometer deactivated)
Measuring accuracy
Switching hysteresis w_N	±5 % of threshold value; min. 0.1 m/s
Setting switching threshold w_N	Potentiometer (270°); optionally fix pre-programmed
Threshold pre-programmed w_N	±3 % of measuring value + 0.1 m/s ²⁾
Response time (t₉₀) w_N	3 s (jump of w_N from 0 to 5 m/s in air)
Switch-on delay	20 s
Temperature gradient w_N	< 2 K/min (at w_N = 5 m/s in air)
Operating temperature
Sensor	-20 … +85 °C
Electronics	-20 … +70 °C
Storage temperature	-20 … +85 °C
Material
Enclosure	PBT (glass-fibre reinforced)
Sensor tube	Stainless steel 1.4571
Sensor head	PBT (glass-fibre reinforced), stainless steel 1.4571
Protective coating (optional)	Polyurethane derivative
Sensor cable	PVC
General data
Humidity	Measuring mode: Non-condensing (< 95 % RH)
Operating pressure (max.)	0 … 10 bar (overpressure)
Display	LED green: Operating status; LED red: Switching status / sensor defective
Supply voltage	24 V DC ± 20 %
Current consumption	Typical 40 mA (max. 70 mA, without signal current of relais output)
Switching output	Semiconductor relais; max. 30 V / 100 mA / 300 mW R_ON,max = 25 Ω
Electrical connection	Non-detachable cable, 4 wires, length 2 m, with ferrules
Maximum cable length	100 m max.
Mounting position	Arbitrary
Minimum immersion depth	58 mm (< 58 mm on request)
Protection type	Sensor probe: IP67; Enclosure: IP65 (with installed rubber plug)
Protection class	III (SELV) or PELV (EN 50178)
MTTF value (per 01.01.2011)	> 50 years
Probe length L	100/200/350/500 mm
Weight	Approx. 100 g (L = 350 mm)

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

²⁾ Related to adjustment reference

Subject to technical changes.

Order information

	Description	Article-Number
Basic sensor	SCHMIDT^® Flow Switch SS 20.200; without protective coating	504 475 -	X	Y	S	N xx
Basic sensor	SCHMIDT^® Flow Sensor SS 20.200; with swichting output, cable length 2 m, with protective coating	505 504 -	X	Y	S	N xx
	Options
Mechanical Type	Sensor length 100 mm		1
	Sensor length 200 mm		2
	Sensor length 350 mm		3
	Sensor length 500 mm		4
Measuring range	Measuring range 0 … 1 m/s			1
	Measuring range 0 … 2.5 m/s			2
	Measuring range 0 … 10 m/s			3
	Measuring range 0 … 20 m/s			4
Signalization relais/LED	Flow velocity w_N above switching threshold: relais closes / LED on				1
	Flow velocity w_N above switching threshold: relais opens ¹⁾ / LED on				2
	Flow velocity w_N below switching threshold: relais closes / LED on				3
	Flow velocity w_N below switching threshold: relais opens ¹⁾ /LED on				4
Setting threshold	With setting potentiometer, without pre-setting					P 00
	With setting potentiometer, selectable pre-setting from 5 up to 95% of measuring range					P 05 … 95
	Selectable pre-programming (not changeable) from 5 up to 95% of measuring range					F 05 … 95

¹⁾ The configuration “open relay” in case of an alarm is called a “fail-safe” because both a power failure and a cable break can be signalized as an alarm as well.

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, galvanized steel	301 048
Wall mounting flange, stainless steel, PTFE clamp ring	520 181
Compression fitting, stainless steel, G½, atmospheric pressure	532 160
Compression fitting, brass, G½, atmospheric pressure	517 206
Compression fitting, stainless steel, G½, max. 10 bar, with protection against pressure losses	524 919
Compression fitting, brass, G½, max. 10 bar, with protection against pressure losses	524 891
Welding sleeve, steel, G½, according to EN 10241, 5 pieces	524 916
Welding sleeve, stainless steel, G½, according to EN 10241, 2 pieces	524 882

Miscellaneous

Description	Article-Number
Clip-on bars for protection of sensor head against mechanical impacts, stainless steel	531 026
Attachable 2-wires-clip for protection of sensor head against mechanical impacts, stainless steel, H₂O₂-resistant	559 124