Technical Documentation OVERFILL PROTECTION SYSTEM > Type 76/NB 220 10/2000Edition: 1 FAFNIR GmbH Bahrenfelder Str. 19 Օ D-22765 Hamburg Telephone: +49 (0)40-39 82 07-0 Օ Telefax: +49 (0)40-3 90 63 39 size="-3">

Overfill Protection System Type 76/NB 220 >

certified in accordance with the German Water Resources Act(WHG), is a self-contained safety system that is designed to prevent storage tanks and process tanks from being overfilled by monitoring them constantly.It can be used in all storage tanks containing liquids which aresubject to the Water Resources Act (see Section 7 "Technical data") (in storage tanks with a capacity of over 1,000 litres) because the monitoring of such tanks by an overfill protection system is stipulated by law in some countries.This overfill protection system consists of a level detector insidethe tank and a wall-mounted...

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Before putting into operation all the devices belonging to theOverfill Protection System must be checked to ensure that they have been connected up correctly and are operating properly. The power supply, including that of downstream equipment, must also be checked.Parts of the Overfill Protection System which are not checkedmust meet the certification requirements for overfill protectionsystems.The specialised contractor or user of the overfill protectionsystems may only use such parts of the system without a test symbol as comply with the General Building Standards and the Special Building Standards...

The Type 76/NB 220 Overfill Protection System consists of a leveldetector and a transducer with a binary output. The Type NB220 QS and NB 220 QSF transducers also have an alarm unit with visual and audible signal generators.The switching signal is fed to the annunciator or the controldevice with actuator direct or via a signal amplifier if necessary (see Fig. 1). > E (1)(2)(5a)(5b)(5c)Binary signal(4) C) and two minutes (at anambient temperature of -25 > Fig. 1: Layout of the Overfill Protection System C). > The transducer consists of a sensor (encapsulated PTC resistor) and a probe tube which...

Response length L Response length L LiYY 2 x 1 cableStandard, 3 m long Elbow coupling Conduit thread PG 11 Maker's plate Probe lengthpunched > Marking groove LiYY 2 x 1 cableStandard, 3 m long LiYY 2 x 1 cableStandard, 3 m long Fixing screw > 5010Probe length Response lengthpunchedG 3/4 > 4270 Spanner size 36 Probe lengthpunched Spanner size 41 > 4010 Marking groove Spanner size 27 G1 Fixing screw > 28 Spanner size 27 > Probe length G 3/4 > Response length L PTC resistorProbe tube Threshold point > Response length L Response length L PTC resistorProbe tube PTC resistorProbe tube > 35 Threshold...

C to +50 CH=Temperature of liquid -25 C to +80 CThe level detectors have a clampable screw-in body (G 1 andG3/4) with which the particular response length can be set for the respective tank by sliding the probe tube inside the screw-in body (see Figs. 2a/2b and Section 4 "Installation"). This does not apply to Type 76 M where the probe tube is fixed to the inside of the screw-in body. Apart from the standard version (A), Type 76 transducer is alsoavailable in other versions (S/W/C/M) (see Figs. 2a and 2b). In addition, all the level detectors can be supplied in two different temperature ranges:...

Type NB 220 QSF transducer The Type NB 220 QSF transducer has an integrated scannerwhich constantly monitors operation of the PTC resistor. The properties of the PTC resistor, e.g. temperature rise and drop characteristics, are checked several times per second without affecting the live measuring process. The test function ensures that any PTC resistors which are no longer operating reliably on account of external influences (corroded sensor sleeve) are immediately detected and reported by causing the Overfill Protection System to respond. Since the power fed to the PTC resistor via the scanner...

The permissible degree of filling is calculated in accordance with the German Technical Rules for Combustible Liquids TRbF 280, para. 2.2. Take the operating delay time into account (see Section 7 "Technical data"). > Once the level detector has been fitted, the setting ofresponse length (L), using the reference dimension (Y) (=distance between the marking groove at the top of the probe tube and the hexagonal support of the screw-in body) and the punched probe length (Z), can be checked to make sure it is correct, without removing the sensor. L = Z - Y > Since the response length (L) of the Type...

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Check the Overfill Protection System at regular intervals,but at least once a year, to ensure that it is in good working order. It is the users responsibility to choose the type of test and the intervals. Type NB 220 QSF transducer can be checked to make surethat it is working properly by pressing the "Test" button (see next section "Type NB 220 QSF transducer"). > For further information about methods of testing, please refer to VDI/VDE Guideline 2180, Sheet 4. > 16 > Overfill Protection System Type 76/NB 220 size="-1">

certification rules for overfill protection systems (see Fig. 5). On the Type 220 QS transducer external annunciators and control units must be placed between terminals 4 and 8 of the device to monitor the supply of auxiliary power in accordance with the > Overfill Protection System Type 76/NB 220 17 >

< 2 secondsTemperature rise time/release time at ambient temp.: < 2 min at -25 C, < 15 sec at +80 CHousing protection:IP 67 > Temperature range:Media: -25 C to +50 C, -25 C to +80 CPressure range:0 to 2 bar Media compatibility:For combustible liquids:Diesel fuel (DIN 51 601); light fuel oil (DIN 51 603, Part 1) used transmission oils and engine oils; hexanol 1; aceto-acetic ethyl ester (aceto-acetic ester); acrylic acid-2-ethyl hexyl ester (2-ethyl hexyl acrylate); cyclohexyl acetate; benzaldehyde; aceto- acetic methyl ester; nitrobenzene; 1.2- dichlorobenzene; 2.4-dimethylaniline (N,N-dimethylaniline);...