Siemens SITRANS F M MAG 3100 sensor Operating Instructions Manual

Siemens SITRANS F M MAG 3100 sensor Operating Instructions Manual

Electromagnetic flowmeters
Hide thumbs Also See for SITRANS F M MAG 3100 sensor:

Advertisement

Quick Links

SITRANS F
Electromagnetic Flowmeters
SITRANS F M MAG 3100 sensor
Operating Instructions
Edition
09/2012
Answers for industry.

Advertisement

Table of Contents
loading

Summary of Contents for Siemens SITRANS F M MAG 3100 sensor

  • Page 1 SITRANS F Electromagnetic Flowmeters SITRANS F M MAG 3100 sensor Operating Instructions Edition 09/2012 Answers for industry.
  • Page 3 ___________________ SITRANS F M MAG 3100 sensor Introduction ___________________ Safety notes ___________________ Description SITRANS F ___________________ Installing/Mounting Electromagnetic Flowmeters ___________________ SITRANS F M MAG 3100 sensor Connecting ___________________ Service and maintenance Operating Instructions ___________________ Troubleshooting/FAQs ___________________ Technical data ___________________ Spare parts/Accessories...
  • Page 4 Note the following: WARNING Siemens products may only be used for the applications described in the catalog and in the relevant technical documentation. If products and components from other manufacturers are used, these must be recommended or approved by Siemens. Proper transport, storage, installation, assembly, commissioning, operation and maintenance are required to ensure that the products operate safely and without any problems.
  • Page 5: Table Of Contents

    Installation with earthing flanges....................30 Connecting .............................. 33 General safety requirements......................33 Remote installation ........................35 Installation check .........................37 Potting ............................38 Service and maintenance ........................39 Maintenance..........................39 Recalibration ..........................39 Transportation/storage.........................39 Unit repair.............................40 Technical support.........................40 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 6 Dimensions and weight ....................... 59 Spare parts/Accessories .......................... 65 Ordering ............................65 Factory settings ............................67 Flange mating dimensons (metric)......................69 Coil resistance ............................71 Glossary ..............................73 Index................................ 75 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 7: Introduction

    2. Make sure the scope of delivery, and the information on the type plate corresponds to the ordering information SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 8: History

    The contents of these instructions are regularly reviewed and corrections are included in subsequent editions. We welcome all suggestions for improvement. The following table shows the most important changes in the documentation compared to each previous edition. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 9: Further Information

    Product information on the Internet The Operating Instructions are available on the CD-ROM shipped with the device, and on the Internet on the Siemens homepage, where further information on the range of SITRANS F flowmeters may also be found: Product information on the internet (http://www.siemens.com/flow)
  • Page 10 Introduction 1.3 Further Information SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 11: Safety Notes

    Material compatibility Siemens Flow Instruments can provide assistance with the selection of wetted sensor parts. However, the full responsibility for the selection rests with the customer and Siemens Flow Instruments can take no responsibility for any failure due to material incompatibility.
  • Page 12 Compliance with PED directive "Pressure Equipment Directive" (PED) is mandatory for all pressure equipment sold within the EU and EFTA. Siemens Flow Instruments products complies to PED as stated in the following table. Table 2- 1 MAG 3100 PED Compliance...
  • Page 13: Installation In Hazardous Area

    ● Ex de* [ia] [ib] ia ib* IIC T3-T6 Gb Ex tD A21 IP67 T**°C (** pipe temperature +13 K, but not less than 85°C) (compact mounted) * The "e" and "ib" markings on the compact version are only applicable if the "Ex e" supply/data terminal chamber option is used. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 14 With intrinsically safe circuits, use only certified meters appropriate for the transmitter. If a non-conforming supply unit is used, the "fail-safe" type of protection will no longer be effective and the approval certification will be invalid. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 15 ● Sensor insulation thickness is max. 100mm (only insulated sensors). ● IEC/EN 61241-14 and 61241-17 are considered for installation in areas with combustible dust. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 16 Connect the devices that are operated in hazardous areas as per the stipulations applicable in the country of operation, e.g. for Ex "d" and "nA", permanent cables must be laid. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 17: Certificates

    Safety notes 2.3 Certificates Certificates Certificates are posted on the Internet and on the documentation CD-ROM shipped with the device. See also Certificates (http://www.siemens.com/processinstrumentation/certificates) SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 18 Safety notes 2.3 Certificates SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 19: Description

    The SITRANS F M range of add on modules, presently including HART, Foundation Fieldbus. MODBUS RTU RS 485, PROFIBUS PA / DP and Devicenet, are all applicable with the SITRANS F M MAG 6000 transmitter. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 20: Design

    ● Hastelloy C276 or C22 ● AISI 316Ti (1.4571) ● Platinum / Iridium ● Titanium ● Tantalum The sensors carry a wide range of approvals, see Technical data (Page 47). SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 21: Theory Of Operation

    ASIC with 23 bit signal resolution. This has eliminated the need for range switching. The dynamic range of the transmitter is therefore unsurpassed with a turn down ratio of minimum 3000:1. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 22 Description 3.3 Theory of operation SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 23: Installing/Mounting

    Determining a location Note The sensor must always be completely filled with liquid. Figure 4-1 Correct installation with filled pipes SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 24 To achieve accurate flow measurement it is essential to have straight lengths of inlet and outlet pipes and a certain distance to pumps and valves. It is also important to centre the flowmeter in relation to pipe flanges and gaskets. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 25 4.2 Determining a location Installation in large pipes The flowmeter can be installed between two reducers (e.g. DIN 28545). At 8° the following pressure drop curves apply. The curves are applicable to water. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 26: Orienting The Sensor

    A flow of 3 m/s (V) in a sensor with a diameter reduction from DN 100 to DN 80 (d = 0.8) gives a pressure drop of 2.9 mbar. Orienting the sensor The sensor operates in all orientations, but Siemens has the following recommendations: ● Vertical installation with an upwards flow Figure 4-3 Vertical orientation, upwards flow...
  • Page 27: Removing The Liner Protectors

    After only a few hours without the blanks, the liner will creep back towards its original shape and installation will be more difficult to carry out. Figure 4-5 Sensor with wooden blanks SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 28 Sensor with blanks ● Remove the blanks immediately before mounting the sensor Figure 4-8 Removing blanks NOTICE Do not use sharp objects to remove the blanks as this can damage the liner! SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 29: Mounting

    ● Use proper gaskets according to liner type Figure 4-9 Correct installation with gaskets Vibrations Avoid strong vibrations. Figure 4-10 Avoid vibrations CAUTION In applications with strong vibrations, Siemens recommend remote mounting of the transmitter! SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 30 Table 4- 1 Maximum allowable torques PN 6 PN 10 PN 16 PN25 PN 40 PN 63 ANSI Cl AWWA Inch F/lb F/lb F/lb F/lb F/lb F/lb F/lb F/lb ½ 1½ 2½ SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 31: Potential Equalization

    Potential equalization with earthing electrodes Cathodic protected piping Special attention must be paid to systems with cathodic protection WARNING Use in hazardous area! Cathodic pipe protection is not allowed in hazardous areas SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 32: Installation With Earthing Flanges

    Only sensors with PTFE or PFA liners Installation with earthing flanges is only relevant for sensors with PTFE or PFA liners ● Mount earthing flanges where necessary on non conductive pipes. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 33 ● Connect the earthing flanges to the sensor with the enclosed earthing straps. Earthing strap connection on flat earthing Earthing strap connection on type E earthing rings rings Note Abrasive liquids In special cases the earthing flanges can work as inlet protection. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 34 4.7 Installation with earthing flanges NOTICE High temperature sensors High temperature sensors are delivered with two factory mounted earthing flanges. No further action need to be taken for potential equalisation. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 35: Connecting

    It must be marked as the disconnecting device for the equipment. Note Hazardous area applications Special requirements apply to the location and interconnection of sensor and transmitter. See "Installation in hazardous locations". SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 36 ● The line length from the cable gland to the terminals must be kept as short as possible. Line loops in the terminal box must be avoided. ● To guarantee the IP 67 degree of protection, use cables with the required specifications. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 37: Remote Installation

    Cable data (Page 54) Remote installation Note Remote installation only The following applies to remote installation of MAG 5000 / 6000 or MAG 6000 I. 1. Unscrew and remove terminal box lid. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 38 3. Fit the ½" NPT or M20 cable glands for supply and output cables. 4. Fit and connect electrode and coil cables as shown below. Sensor Electrode cable Coil cable Only required for ATEX applications SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 39: Installation Check

    Before commissioning it must be checked that: ● The device has been installed and connected in accordance with the guidelines provided previous in this chapter and in chapter 4 Installing/mounting . See also Connecting (Page 33) SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 40: Potting

    ● Let cure for approximately 24 hours at approximately 25°C (77°F). Curing time increases by 100% per -10°C (-18°F). Horizontal orientation Vertical orientation Note Gel can be penetrated with test instruments or be removed in case of cable replacement. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 41: Service And Maintenance

    Repair and service must be carried out by Siemens authorized personnel only. Note Siemens defines flow sensors as non-repairable products. Recalibration Siemens A/S Flow Instruments offers to recalibrate the sensor. The following calibrations are offered as standard: ● Standard matched pair calibration Note For recalibration the memory unit must always be returned with the sensor.
  • Page 42: Unit Repair

    Figure 6-1 Handling of sensor Unit repair NOTICE Repair and service must be carried out by Siemens authorized personnel only. Note Siemens defines flow sensors as non-repairable products. Technical support If you have any technical questions about the device described in these Operating Instructions and do not find the right answers, you can contact Customer Support: ●...
  • Page 43: Return Procedures

    ● Information about field service, repairs, spare parts and lots more under "Services." Additional Support Please contact your local Siemens representative and offices if you have additional questions about the device. Find your local contact partner at: http://www.automation.siemens.com/partner See also Local contact person (http://www.automation.siemens.com/partner)
  • Page 44 Shipments without a declaration of decontamination shall be cleaned professionally at your expense before further proceeding. You can find the forms on the Internet and on the CD delivered with the device. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 45: Troubleshooting/Faqs

    ● A low megger reading would indicate the coil insulation is braking down. This is normally due to fluid ingress into the coil housing. ● Sensors with an insulation resistance down to 1 MΩ may still work satisfactorily but this is not guaranteed. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 46 For sensors removed from line with dry bore, use megger between terminal 82 and compression plate, and 83 and compression plate to show any water ingress behind electrodes or within enclosure. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 47: Fluctuating Process Values

    – Connect the electrode cable (82, 83, 0 and shield) according to the instructions in chapter Connecting (Page 33) Note Vibrating environments It is recommended to use special low noise cables for sensor sizes DN 2 and 3 installed in vibrating environments. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 48 Troubleshooting/FAQs 7.2 Fluctuating process values SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 49: Technical Data

    Ex) Test pressure 1.5 x PN (where applicable) 1.5 x PN (where applicable) 1.5 x PN (where applicable) Pressure drop at 3 m/s As straigth pipe According to 2004/108/EC SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 50 PN 35 (DN 50 ... 600,  35 bar (508 psi)) JIS B 2220:2004 K10 (½" ... 24")  K20 (½" ... 24")  Other flanges and pressure On request On request ratings SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 51 0.01 ... 40 bar ® (0.15 ... 580 psi) Ebonite 0.01 ... 100 bar (0.15 ... 1450 psi) Maximum operating pressure decreases with increasing operating temperature and with stainless steel flanges SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 52 -40 … +70 °C (-40 … +158 °F) For temperatures below -20 °C (-4 °F) AISI 304 or 316 flanges must be used Ebonite 0 … 95 °C (32 … 203 °F) SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 53 Standard fibre glass Stainless steel AISI 316    version only) reinforced polyamide reinforced polyamide (1.4436) Stainless steel AISI 316 Stainless steel AISI 316   (1.4436) (1.4436) Cable entries SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 54 PED) – 97/23 conforms to PED) – 97/23 conforms to PED) – 97/23 EC1) CRN EC1) CRN EC1) CRN Material certificate EN On request On request On request 10204 3.1 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 55 1) For sizes larger than 600 mm (24") in PN 16 PED conformity is available as a cost-added option. The basic unit will carry the LVD (Low Voltage Directive) and EMC approval. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 56: Cable Data

    1.5 mm 0.25 mm Shield Double Color code Brown, blue, black Brown, blue, black Outside color Grey Grey Ext. diameter 7.8 mm 8.1 mm Conductor Flexible CU Flexible CU Isolation material SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 57: Pressure / Temperature Range

    Metric measures (pressure in bar) - Sizes 25 mm, 40 mm and >300 mm Flange Flange rating Temperature (°C) specifications EN 1092-1 PN 10 10.0 10.0 PN 16 16.0 16.0 15.5 15.1 PN 40 40.0 40.0 38.7 37.7 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 58: Process Fluid Conductivity

    150 lb AWWA C-207 Class D 150l Process fluid conductivity Compact installation Liquids with an electrical conductivity ≥ 5 μS/cm. Remote installation Standard cable [µS/cm] Conductivity of medium [ft] Cabel length SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 59: Liner Selection

    Drinking Water, Wastewater, Chemicals, Food & Beverage, Pulp & Paper Drinking Water, Wastewater, Chemicals, Food & Beverage, Pulp & Paper Linatex Abrasive media Soft rubber Drinking Water, Wastewater, Abrasive media, Chemicals SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 60: Electrode Selection

    Chemicals, Food & Beverage, Pulp & Organic acids, Alkalis, Diluted salts Paper Platinum Drinking Water, Wastewater, Reducing acids, Oxidicing acids, Chemicals, Food & Beverage, Pulp & Organic acids, Alkalis, Diluted salts Paper SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 61: Dimensions And Weight

    23.4 13.8 24.2 19.4 25.4 12.6 28.2 21.4 27.4 17.8 32.2 22.5 28.5 21.9 34.3 23.9 30.0 22.1 36.5 25.7 31.7 24.9 1032 40.7 1000 27.7 35.7 26.4 1136 44.8 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 62 23.6 600/ - 23.6/ - 26.8 23.6 600/ - 23.6/ - 31.5 27.6 875 / 31.5 / 27.6 31.5 1000 / 39.4 / 31.5 35.4 1125 / 49.2 / 35.4 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 63 13.8 13.8 13.8 13.8 13.8 17.7 17.8 17.8 17.8 17.8 19.7 19.7 19.7 19.7 19.7 21.7 21.7 21.7 21.7 21.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 25.2 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 64 :PN 35 DN 500 = 680 mm :PN 35 DN 600 = 750 mm :Not AS 4087 PN 21 or PN 35 Table 8- 18 Grounding rings Nominal size Wgt. inch inch inch inch 1½ 2½ SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 65 = Type C grounding ring = Type E grounding ring (included and factory-mounted on high-temperature 180 °C PTFE sensor) = Flat type grounding rings :Weights are approx. (for PN 16) without transmitter SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 66 Technical data 8.6 Dimensions and weight SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 67: Spare Parts/Accessories

    Spare parts/Accessories Ordering In order to ensure that the ordering data you are using is not outdated, the latest ordering data is always available on the Internet: Process instrumentation catalog (http://www.siemens.com/processinstrumentation/catalogs) SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 68 Spare parts/Accessories 9.1 Ordering SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 69: Factory Settings

    706.8 28274 1100 14000 855.2 34211 1200 15000 1017.8 40715 1400 25000 1385.4 55417 1500 30000 1590.4 63617 1600 35000 1809.5 72382 1800 40000 2290.2 91608 2000 45000 2827.4 113097 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 70 318689.6 US GPM 1000 US G US MG 1800 176115 10083.5 403341.5 US GPM 1000 US G US MG 2000 198129 12448.8 497952.5 US GPM 1000 US G US MG SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 71: Flange Mating Dimensons (Metric)

    Flange mating dimensons (metric) Figure B-1 Flange mating dimensions Table B- 1 Flange mating dimensions (metric) Dimensions (mm) Bolting Holes Bolts PN10 1015 1115 1050 1000 1230 1160 1200 1455 1380 PN16 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 72 Dimensions (mm) Bolting Holes Bolts 1025 1125 1050 1000 1255 1170 1200 1485 1390 PN40 150 lb 36.5 AWWA 1060 1168 1068 1000 1289 1200 1050 1346 1257 1200 1511 1422 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 73: Coil Resistance

    DN800 32" -25/+60 DN900 36" -25/+60 DN1000 40" -25/+60 DN1100 44" -25/+60 DN1200 48" -25/+60 DN1400 54" -25/+60 DN1500 60" -25/+60 DN1600 66" -25/+60 DN1800 72" -25/+60 DN2000 78" -25/+60 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 74 Coil resistance SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 75: Glossary

    Normenarbeitsgemeinschaft für Meß- und Regeltechnik in der Chemischen Industrie (NAMUR). NAMUR is a group representing the interests of the chemical industry which create standards for instrumentation and electrical devices used in industrial plants. SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 76 10:1. Therefore the meter requires a turndown ratio of at least 10:1. USM II is a Communication Platform. The Siemens USM II concept enables fitting of add-on bus modules without loss of functionality: 1.
  • Page 77: Index

    In hazardous area, 33 Support, 41 Remote installations, 35 Intrinsically safe data, 12 Safety instructions, 33 Introduction, 5 Electrode Items supplied, 5 Material, 18, 58 Electrode resistance check, 44 Empty pipe detection, 25 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 78 Protective conductor terminal, 35 Protective earth, 35 Recalibration, 39 Repair, 39, 40 Return procedures, 41 Safety Instrument safety standards, 9 Sensor installation, 21 Safety instructions Electrical connection, 33 Safety notes, 9 SITRANS F M MAG 3100 sensor Operating Instructions, 09/2012, A5E03005599-02...
  • Page 79 For more information www.siemens.com/flow Siemens A/S Subject to change without prior notice Flow Instruments Order No.: A5E03005599 Nordborgvej 81 Lit. No.: A5E03005599-02 DK-6430 Nordborg © Siemens AG 09.2012 *A5E03005599* A5E03005599 www.siemens.com/processautomation...

Table of Contents