Liquid level switch BM 34

Transcription

1 KROHNE 09/ GR/PRINTO Liquid level switch Status: 10/99 Variable area flowmeters Vortex flowmeters Flow controllers Electromagnetic flowmeters Ultrasonic flowmeters Mass flowmeters Level measuring instruments Communications engineering Engineering systems & solutions

2 Liquid level switch For use in potentially hazardous environments Operating principle A float guided on a non-magnetic tube follows the level of the liquid surface, thereby actuating up to 6 reed contacts, monostable or bistable, inside the tube via a built-in magnet system. Types of contacts All contacts are fitted to a rod with a clamping device. Where switching points are not known or the contact has to be adjustable the clamps are loosely attached. For overfill protection systems, the uppermost contact is non-detachable. The length of the guide tube and installation height of the reed contacts are specified from the lower edge of the screw connection or mounting flange. Approved for hazardous duty and as part of an overfill protection system Up to 6 freely adjustable or preset switching elements Temperature range C ( F) and operating pressure max. 40 bar (580 psig) m (1 20 ft) tube length Monostable reed contacts These switches are only actuated as long as the float and magnetic system are at an equal height. If the float moves away, the contact returns to its original setting. The achieved switching state can be maintained with an auxiliary relay. Floats with a ring magnet system are used. Bistable reed contacts These switches are actuated by the float s magnetic system and remain in the switching state. Therefore, they provide a clear indication of the float s location, i.e. above or below the switch, without the need for an auxiliary relay. The switch setting is retained until the float moves past the switch in the opposite direction. Floats with a radial magnetic system are used. A variety of materials permits use also in aggressive media Float with ring magnet system Float with radial magnet system 34

3 Range of application is ideal wherever liquid levels need to be monitored in process and storage tanks. Typical liquids are: Water and aqueous fluids Acids / alkalis Organic and inorganic solvents Special versions Interface detection, TS If two liquids with different densities are stored in one tank, the level of the interface can be measured using a special interface-type float. The weight and buoyancy of the float are such that it floats on the heavier and sinks in the lighter liquid. The minimum difference in density between both liquids should be greater than 100 g/l (6.24 lb/ft 3 ), and the float must be fully immersed in the light liquid. If the lighter liquid is not always stored in the tank, this must be specified on ordering to ensure appropriate float design. For ships tank with test device, /T In the /T version, an additionally installed rod magnet in the tube can be raised with a test knob. By means of a magnetic coupling, a sleeve on the outside of the tube follows this motion. It is thus possible to raise the float to contact point, thus permitting a check of the instrument s switching functions. If the float has developed a leak and filled with liquid, the magnetic coupling breaks off due to the heavier weight and no contact is produced. Guide tube centering aid For agitated liquids, a centering device welded to the tank bottom is recommended to avoid buckling of the guide tube. For approved devices, a bottom centering device is mandatory where the length of the guide tube is > 3000 mm (> 9.8 ft). Product Overview Vibration Continuous, non-contact Switches Ultrasonic Radar Ultrasonic Buoyancy Capacitance Materials /coatings For use in aggressive products, all wetted parts can be coated with PVC, PP or PTFE. Other materials are titanium or Hastelloy-C4. Continuous, contact Ultrasonic Buoyancy TDR Dimensions in mm (inches) 35

4 Responsibility for suitability and intended use of our instruments rests solely with the purchaser. Technical data Length (guide tube) m ( ft) Switching accuracy ± 3 mm (± 0.12 ) Max. allowable operating pressure Standard max. 40 bar (580 psig) /F/WB, /F/WN max. 3 bar (43.5 psig) /Ex/Z0, /F/Ex/Z0 max. 35 bar (508 psig) depending on flange pressure rating and float pressure resistance. Process temperature Standard C ( F) Option C ( F) /Ex/Z C ( F) /F/WB C ( F) /F/WN C ( F) /F/Ex/Z C ( F) Operating data Min. density Standard, /Ex/Z0 0.4 kg/l (25 lb/ft 3 ) Option, /F/WB, /F/WN, /F/Ex/Z0 0.5 kg/l (31 lb/ft 3 ) Viscosity* Standard 5000 m Pa s For approved instruments 1000 m Pa s Solids content* 100 g/l (6.24 lb/ft 3 ) =^ 10% dry substance Particle size* 200 µm Reed contacts Type/number max. 6 monostable or 6 bistable changeover contacts (bistable contact not possible with F/WN, F/WB or F/Ex/Z0) Version Standard F/WN, F/WB Ex/Z0, F/Ex/Z0 Operating voltage 65 V 30 V 20 V Max. contact rating 40 W / 60 VA 0.9 W (VA) 200 mw (VA) Max. current switched 1 A 30 ma 40 ma Contact spacing monostable changeover contact > 50 mm (1.97 ) bistable changeover contact > 70 mm (2.76 ) Switching hysteresis 5 mm (0.2 ) Holding range 17 mm (0.67 ) Lowermost switching point < guide tube length 130 mm (5.12 ) Uppermost switching point > 100 mm (3.94 ) distance from bottom edge of flange Connection Standard DIN 2501, Form C DN 25, PN 40 Option DIN 2501, Form C DN 40 DN 150/PN 6 PN 40 ANSI B /300 lb/rf DIN 2999 G 11/2 A (SW 50 mm wrench) Plastic-coated flanges DIN 2501, Form C DN 50/PN 6 PN 40 ANSI B /300 lb/rf /T DIN 2501, Form C DN 50/PN 40 ANSI B /300 lb/rf Information on higher pressure ratings and other standards available on request Protection category to EN / IEC 529 IP 56, equivalent to NEMA 3 Materials Flanges Screw connection Guide tube Float Housing Stainless steel (316 Ti) Stainless steel (316 Ti)/titanium plated Stainless steel coated with PVC, PP or PTFE Stainless steel (316 Ti) See instrument versions See Selection of float type Stainless steel (316 Ti) * Relevant for instruments approved as part of an overfill protection system. 36

5 Selection of float type Shape Dimensions Materials Min. density Max. allowable Product temperature (diameter x height x wall-thickness) operating pressure min. max. in mm in inches kg/l lb/ft 3 bar psig C F C F Standard versions without explosion protection Cylinder 97 x 145 x x 5.71 x 0.04 Stainless steel (316 Ti) Cylinder 97 x 145 x x 5.71 x 0.02 Stainless steel (316 Ti) Ball 142 x 145 x x 5.71 x 0.03 Stainless steel (316 Ti) Ball 142 x 145 x x 5.71 x 0.04 Stainless steel (316 Ti) Cylinder 97 x 145 x x 5.71 x 0.04 Titanium Ball 142 x 145 x x 5.71 x 0.04 Titanium Cylinder 94 x x 3.94 PVC Cylinder 94 x x 3.94 PP Cylinder 130 x x 6.50 Hard glass Cylinder 94 x x 3.94 PVDF Cylinder 140 x 175 x x 6.89 x 0.04 Hastelloy-C /T Ball 142 x 145 x x 5.71 x 0.04 Titanium Instrument approved for use in Zone 0 (EC) /Ex/Z0 Cylinder 97 x 145 x x 5.71 x 0.04 Stainless steel (316 Ti) Cylinder 97 x 145 x x 5.71 x 0.02 Stainless steel (316 Ti) Ball 142 x 145 x x 5.71 x 0.03 Stainless steel (316 Ti) Ball 142 x 145 x x 5.71 x 0.04 Stainless steel (316 Ti) Ball 97 x 145 x x 5.71 x 0.04 Titanium Ball 142 x 145 x x 5.71 x 0.04 Titanium Instruments approved as part of an overfill protection system /F/Ex/Z0 Cylinder 97 x 145 x x 5.71 x 0.04 Stainless steel (316 Ti) Ball 142 x 145 x x 5.71 x 0.04 Stainless steel (316 Ti) Cylinder 97 x 145 x x 5.71 x 0.04 Titanium Ball 142 x 145 x x 5.71 x 0.04 Titanium /F/WB Cylinder 97 x 145 x x 5.71 x 0.04 Stainless steel (316 Ti) Ball 142 x 145 x x 5.71 x 0.04 Stainless steel (316 Ti) Cylinder 97 x 145 x x 5.71 x 0.04 Titanium Ball 142 x 145 x x 5.71 x 0.04 Titanium /F/WN Cylinder 97 x 145 x x 5.71 x 0.04 Stainless steel (316 Ti) Ball 142 x 145 x x 5.71 x 0.04 Stainless steel (316 Ti) Cylinder 140 x 170 x x 6.69 x 0.04 Hastelloy-C Cylinder 97 x 145 x x 5.71 x 0.04 Titanium Ball 142 x 145 x x 5.71 x 0.04 Titanium Product Overview Vibration Continuous, non-contact Switches Ultrasonic Radar Ultrasonic Buoyancy Capacitance Continuous, contact Ultrasonic Buoyancy TDR Important! The specified max. allowable operating pressure applies to 20 C or 68 F only! Float test pressure = 1.3 times the max. allowable operating pressure. Hazardous-duty units = 1.5 times the max. allowable operating pressure. 37

6 Instrument versions Version /RR /R* /R-PVC BM 24 R-PP (not approved) (not approved) Flange Stainless steel Screw connection Stainless steel Stainless steel (316 Ti) Stainless steel (316 Ti) (316 Ti) (316 Ti) with PVC face with PP face Guide tube Stainless steel Stainless steel Stainless steel Stainless steel material (316 Ti) (316 Ti) (316 Ti) / with PVC tube (316 Ti) / with PP tube Guide tube dimensions mm x x x 1.50 / x x 1.50 / x 1,80 inches 0.84 x x x 0.06 / 0.98 x x 0.06 / 0.98 x 0.07 Weight ** approx. kg approx. lb Version /R-PTFE /R-Titan /R-Hastelloy-C4 (not approved) Flange Stainless steel Stainless steel Stainless steel (316 Ti) (316 Ti) (316 Ti) with PTFE face titanium plated Hastelloy-C4 plated Guide tube material Stainless steel Titanium Hastelloy-C4 (316 Ti) / with PTFE tube Guide tube dimensions mm x 2.00 /25.00 x x x 1.60 inches 0.84 x 0.08 / 0.98 x x x 0.06 Weight ** approx. kg approx. lb ** Only for standard instruments and those approved for use in Zone 0 ** Weight = Instrument with 1 m (3.3 ft) guide tube length plus 1 kg (2.2 lb) for every additional meter (3.3 ft) tube length Guide tube test pressure = 1.5 times the max. allowable operating pressure at 20 C (68 F). 38

7 Dimensions in mm (inches) /RR Flange version /R Version with screw connection /T For ships tank with test device Product Overview 1 Cap 2 Test knob 3 Wire 4 Reed contact 5 Float 6 Rod magnet 7 Sleeve Vibration Continuous, non-contact Switches Ultrasonic Radar Ultrasonic Buoyancy Capacitance Continuous, contact Ultrasonic Buoyancy TDR 39

8 Approvals Application Instrument version Certification mark With explosion protection / / K.. / Ex / Z0 PTB No. Ex-85 / 2156 X In stationary storage tanks for flammable water pollutants in classes AI, AII and B (excl. CS 2 ), float and guide tube in Zone 0 Overfill protection with explosion protection / / K..- F / Ex / Z0 PTB No. III B / E F In stationary storage tanks for flammable, water pollutants in classes AI, AII and B (excl. CS 2 ), float and guide tube in Zone 0 Overfill protection without explosion protection / / K..- F / WB PTB No. III B / S 1806 F In stationary tanks [max. operating pressure 3 bar (43.5 psig)] for flammable water pollutants in class AIII Overfill protection without explosion protection / / K..- F / WN DIBT Approval Notice Z In stationary tanks [max. operating pressure 3 bar (43.5 psig)] for non-flammable water pollutants PTB = Physikalisch-Technische Bundesanstalt Type code Instrument Liquid level switch Material RR Stainless steel R Stainless steel, screw connection R-PVC PVC version R-PP PP version R-PTFE PTFE version R-Titan Titanium version R-Hastelloy-C4 Hastelloy-C4 version Number of contacts K1 1 contact K4 4 contacts K2 2 contacts K5 5 conatcts K3 3 contacts K6 6 contacts Type of contact W monostable Bi bistable (not approved as part of an overfill protection system) Range of application N normal range (not for approved instruments) Ex/Z0 electrical equipment for use in hazardous areas F/Ex/Z0 hazardous-area electrical equipment as part of an overfill protection system for flammable water pollutants, classes AI, AII, B F/WB part of an overfill protection system for flammable, water pollutants, class AIII F/WN part of an overfill protection system for non-flammable, water pollutants Special versions T Instrument with test device for non-hazardous areas and for ships tanks TS Interface detection (when used in Zone 0, the max. guide tube length is dependent on the float weight). Not approved as part of an overfill protection system. 40