SPECIFICATION FOR AUTOMATIC PRIMING AND OPERATING SYSTEM FOR CENTRIFUGAL PUMPS.

Transcription

1 DRAFT SPECIFICATION NO : RDSO/PE/SPEC/D/PS/ (REV. 0 ) SPECIFICATION FOR AUTOMATIC PRIMING AND OPERATING SYSTEM FOR CENTRIFUGAL PUMPS. 0. FOREWORD 0.1 This specification covers manufacturing and supply of fully tested Automatic priming and Operating system for centrifugal pumps along with its stand-bye or coupled pumps installed by Indian Railways for drinking water. This specification has been prepared for guidance of the Railways to install automation systems for centrifugal pumps. Sources have to be developed by the Railways on their own. 0.2 This specification requires reference to the following standard specifications :- (i) IS : 616 : Safety, requirements for mains operated electronics or related apparatus for house hold and similar general use. (ii) IEC:68-2-6:Basic Environmental Testing procedures Pt. II -Test Fc & guidance vibration (Sinusoidal) All the components/accessories shall comply with the latest Indian standards specification. 0.3 The purpose of the Automatic Priming and operating system is to operate the pair of centrifugal pumps consisting of stand -bye (both not operating simultaneously) automatically to required minimum attention of the pump operators. It is necessary that the working of this system shall have automatic shifting of operation timing in case of power failure to give the pre-set pumping hours i.e. from 0000 Hrs. to 2400 Hrs. The system should be capable of automatic self priming. 0.4 The offered automatic priming and warning system must have highest practicable reliability. Due to severe environmental conditions on different locations in Indian Railways such as dust, humidity, high ambient temperature, electrical surges in supply system, variation in supply voltage etc., attention to minor detail such as use of correct fasteners are as important as major design consideration along with component rating and screening procedure. 0.5 If any deviation from the requirements of this specification are considered necessary in order to improve the performance, reliability, utility of the system, the tenderer should furnish full particulars for consideration of the purchaser. 0.6 The tenderer shall clearly point out deviation with reasons, if any, in his offer from this specification. Unless such deviations are accepted in final contract, the provision of this specification will be binding on the contractor.

2 1.0 SCOPE 1.1 This specification covers design, supply and installation, general features, performa nce requirements and test of a Automatic priming and operating system for its use on mono-block centrifugal water pumps (one + one stand-bye) or coupled pumps. 1.2 The system should be suitable for installation in the pump houses and suitable for operation on available 240 volt, 1-ϕ, 50 Hz. Or 415V, 3-ϕ, 50 Hz. ac. Supply for pumps fitted with DOL/Star Delta starter to start the pumps with coil voltages of either 240V or 415Volts ac. 1.3 The system of the automatic priming and operating system shall comprise of the following:- (a) By Pass Valve of suitable size Nos. (b) Control Panel duly wired consisting of Programmable logic controller/microprocessor based control system along with Selector switches No. (c) Key Level float switch one each for sump, (priming tank and over-head tank) or sensing probes with water as a conducting medium may be used. (d) Pressure Switches suitable up to 30 PSI for pressure sensing (e) Priming tank of about Liters (f) Solenoid Valve for priming tank, Over Head tank and exhaust of air bubbles (i) G.I.Pipes B class and plumbing accessories necessary for automation Nos Nos No Nos. Lot 1.4 The system shall be suitable for indoor installation and for operation at a maximum altitude upto 1000 M at maximum 95% relative humidity. 2.0 TYPE OF SYSTEM :- The type of system is useful for centrifugal pumps (one + one stand-bye) as well as for coupled pumps. 2.1 The system shall be suitable for operation on following existing supply system voltage available in Indian Railways:- ( a) 240V, 1-φ, 50 Hz. ac. supply ± 10%.

3 (b) 415V, 3-φ, 50 Hz. ac. supply ± 10%. With permissible variation as per relevant IS The system shall be suitable to operate with existing fully automatic DOL/Star Delta starters. 2.2 In case the starter type is not clear from the order particulars, the supplier shall ascertain the same from the Indentor /Purchaser. 2.3 The manufacturer/supplier shall furnish the information as per Appendix A along-with the offer. 2.4 Type of Operations : The system should carry out the following functions automatically : Automation of pump switching sensing presence of water in the sump and Over Head tank through water level controller using float switches or sensing probes with water as a conducting medium and depending upon pre set timing and also capable to shift the timings in case of supply failure Automation of priming of the pump prior to Switching ON the pump Protection/Tripping of the system in case of failure of priming or inadequate priming 2.5 Sequence of Automatic Operations : The following sequence of automatic operation should be provided in the system : The system shall be able to operate automatic as per the set Time of Day for the specified/set duration On receiving signal from the tanks, priming shall be started provided there is water in the tank up to set level and water in the Over-Head tank is below pre set level Priming should be completed within the set programmed period there after pump should be started When the priming tank is filled up, Solenoid Valve should be closed such that the priming tank does not over flow An alarm should be provided in the system, to attract the attendant, if discharge pressure does not build up to the required level in the set period and the pump should be automatically switched OFF.

4 An automatic second priming trial feature shall also be provided in the system so that in case of failure of first trial, second trial may be completed automatically Provision of Automatic shifting of operation timings should be provided in the system so that in case of power failure the working of pump/system may be shifted automatically ensuring total pumping hours during the day to be the same The system should automatically switch off the pump when the over head tank is full or there is no water left in the sump System should be capable of accepting change of timings including total duration of pumping. It should also permit operation of pumps in broken spells depending on requirement System should alternate the operation of two pumps i.e after one pump operation, next time the other pump should be operated. It should also have facility to run only one pump also through external switch/push button in case of failure of one of the two pumps. 3.0 GENERAL DESIGN FEATURES : 3.1 The Control Panel in the system should be solid state without the use of any electro mechanical relay/relays. However, By-pass facilities shall be provided for manual operation as and when required so as to operate the pump manually in case of failure of system or additional pumping is required 3.2 The system should work satisfactorily for the voltage as indicated in clause 2.1 above. Further there should not be any damage to the equipment at voltage less than/higher than the specified value for an indefinite period. 3.3 The Control Panel in the system should be so designed that it is capable to withstand the direct short circuit current at the output terminal without any damage to the equipment. The short circuit shall be limited to minimum possible value. The equipment shall function normal after the short circuit at output terminal is removed. 3.4 For priming the pumps from priming tank, filling the priming tank from the main discharge line and removal of entrapped air from the pumps, Solenoid valves as per clause 1.3(f) should be provided in the system. The construction of which should be of Brass forged body, gaskets/seals material of nitrile rubber with the capability to handle fluid in the temperature range form -5 0 C to 80 0 C suitable for operation on 240V, 50 Hz ac. Supply and should have weather proof enclosure conforming to IP: The Control Panel in the system duly fitted with programmable logic controller / Micro processor based control to control the solenoid valves and pumps shall be dust and vermin proof duly painted/powder coated having selector switches and indication lamps (for position of supply as well as different faults which may occur in the system) shall be mounted on the door.

5 3.5.1 The sheet steel used for the panel shall have thickness of at least 1.6 mm and enclosure shall be thoroughly cleaned and given two coats of primer and two coats of paints of approved colour. 3.6 The system shall be provided with Programmable Logic Controller(PLC)/ Micro processor based control suitable for operation on 90V to 265V ac. with in-built supply for input sensors of 24V dc at 55 0 C ambient temperature with 5% - 95% relative humidity. It shall have program memory(eprom), built in rechargeable nickle-cadmium battery and built in real time clock The software for the control system should have built in features for total automation as well as flexibility for manual operation, as and when required. 3.7 Key level float switches suitable for operation on 240V, 50 Hz ac. supply and valid for inductive load of 8 amps( COS φ = 0.4) should be provided in the system for the sump and overhead tank. The material for housing these switches should be non-toxic polypropylene and colours used for float-switch should be non-toxic fluorescent suitable for drinking water. Sealing used for the system should be waterproof molded with ultrasonically welded and hermetically sealed. The switch shall be capable to operate in hard water and up-to maximum temperature of 80 0 C and should be maintenance free. 3.8 The system should be provided with pressure switches to sense the discharge pressure after switching the pump ON to generate signal in case the discharge pressure does not build up to set level in the specified time Pressure switch should have terminal rating of 10A at 240V ac. with an overload capacity of 20 amps. It should be capable to operate for maximum ambient temperature of 55 0 C. 3.9 Priming tank made of PVC conforming relevant IS of liter capacity should be supplied with the system Gate valves of suitable size made of gun metal should be provided in the system for discharge line as well as for by pass facility for the solenoid valves 3.11 INSTALLATION AND COMMISSIONING : Installation and Commissioning of the complete system shall have to be carried out at site by the contractor/user as specified in the tender, by means of supply and fixing of interconnecting pipes with associate fittings, cables and its accessories and other hardware etc. as required to complete the work at site, complete in all respect to put the system in operation as per specified requirements.

6 4. SERVICE CONDITIONS : 4.1 The automatic priming and operating system shall be suitable for Indoor installations as directed by the purchaser. 4.2 The system shall operate satisfactorily under the following conditions : i. Temperature of inside the pump house may be as high as 55 0 C with 100% humidity. It shall operate satisfactorily at 55 0 C as per IEC-571. ii. iii. During dry weather, the atmosphere is very dusty. In coastal and industrial areas, the atmosphere is corrosive. 4.3 The system and its mounting arrangement shall be of robust design to suit all the climatic and local environmental condition. 5 DRAWINGS DATA AND SAMPLES: 5.1 The tenderer shall submit four copies of connection drawings, block diagram and technical data as per Appendix along with internal test results of the offered system for approval to the tenderer. 5.2 The successful tenderer shall submit a prototype sample for inspection/testing and approval by the purchaser or to authorized representative before the bulk supply. Sources have to developed by the Railways on their own. 5.3 The final set of drawings and construction manual are to be supplied with each order. 5.4 Supplier shall also submit 4 copies of maintenance/trouble shooting manual along with operating instructions at the time of supply. 6 GUARANTEE: 6.1 The system shall be guaranteed against defects in design, material, workmanship etc. for a period of 18 months from the date of dispatch or 12 months from the date of commissioning whichever is earlier. 6.2 During the guarantee period all defective parts shall be replaced promptly and free of cost by the purchaser.

7 7 INSPECTION AND TESTS : 7.1 The complete system shall be subjected to the following tests :- i. Visual Inspection. ii. Tests after incorporating all modifications, found necessary. iii. Routine test. iv. Investigation test as specified in contract. 7.2 The tests to be carried out on complete system under various conditions as per the scheme in the table detailed below together with the clause number to which reference should be made :- List of Tests. SR.NO. TYPE OF TEST CLAUSE TYPE TEST ROUTINE TEST 1. Visual Inspection 7.2 Yes Yes, 100% 2. Insulation resistance 7.3 Yes Yes, 100% 3. Performance Test 7.4 Yes 10 % of lot by simulation 7.2 VISUAL INSPECTION Check for general workmanship, fittings, finish and mounting arrangements is as per approved drawings. - Check for proper tightening in the system. - Check that main components i.e. Key level regulator, complete control panel, solenoid valves, by pass valve, priming tank and pressure switch etc. are as per check list supplied by the manufacturer and approved by purchaser. - Check terminals, switches, indications etc. in the control panel are as per approved drawings

8 7.3 INSULATION RESISTANCE : Megger the electronics and control circuit to earth and check the insulation level with 500V megger range and ensure that the insulation resistance are greater than 10Mohms and record the actual values obtained. 7.4 PERFORMANCE TEST : Following tests shall be performed by the consignee at the location after installing the entire system at least at one of the locations to verify the sequence of operation under various conditions as per scheme detailed below: PRIMING : At the pre set time in the real clock, priming for the system should start automatically and pump should start automatically after completion of priming cycle OPERATION OF THE PUMP: The operation of the start and stop of pump should be ensured through the following testing sequence : STARTING OF PUMP : When a minimum water is available at the set level in the bottom tank, the pump should immediately start automatically after the priming cycle is over. However, the water in the overhead tank should be at less than the maximum set level. Check that the pump does not start when water is at set Maximum level in the Over head tank STOPPING OF PUMP : When the water in the overhead tank reaches at maximum set level or when the bottom sump gets empty at the set level, the pump should switch off automatically SYSTEM OF PROTECTION AGAINST PRIMING FAILURE/DRY RUNNING : If after start of the pump, the pressure is not built up within a set time, the pump shall automatically switch OFF and priming cycle should repeat automatically. Even, thereafter, if the required pressure is not built up, the pump shall switch OFF and visual alarm shall be enunciated to this effect The system shall be tested for by-pass facilities for manual operation The system shall be tested for automatic shifting of operation timing in case of power failure by switching off the mains during the pump timings Reduce the water level in the sump below set level. Start the pump. Pump should not start Check that priming tank is getting filled up automatically and water does not over flow.

9 7.4.8 The system shall be provided with the device for preventing dry-run of the pump by means of liquiphant T etc. 7.5 Type tests are to repeated in case of any major change in design. In case of minor changes i.e. change in type, rating of components etc. special Tests agreed by user and manufacturer are to be conducted to ensure their suitability and effectiveness of the modifications. 7.6 INSPECTION : as directed by the consignee. 8 MARKING : The system shall be marked/screen printed with the following information : (i) Type/make : (ii) Contract No.: (iii) Month and year of manufacture: (iv) Input operating voltage range: (v) Wattage (vi) Current (vii) Frequency 9 TRAINING : The contractor shall train, free of cost at least five supervisors / artisans per Railways for operation, maintenance, fault finding, repairing of the system under guidance of skilled engineers during/after the installation of the system at the depot.

10 APPENDIX A 1.0 SOLENOID VALVE 1.1 Construction of Body : 1.2 Construction of Seat : 1.3 Temperature of Water/Fluid : 1.4 Coil Voltage : 1.5 Coil Insulation Class : 1.6 Coil Rating : 1.7 Enclosure Protection Class : 2.0 PROGRAMMABLE LOGIC CONTROLLER(PLC) /MICRO PROCESSOR BASED CONTROL 2.1 Supply Voltage : 2.2 In built Supply for Input/Sensors : 2.3 Short Circuit Protection : 2.4 No. of Input /Output : 2.5 Ambient Temperature : 2.6 Relative Humidity : 2.7 Programme Memory : 2.8 Real Time Clock : 2.9 Battery : 2.10 Self Diagnostics :

11 3.0 KEY FLOAT SWITCHES : 3.1 Operating Volts : 3.2 Current Ratings (i) Resistive Load : (ii)inductive Load : 3.3 Housing Material : 3.4 Colour : 3.5 Sealing : 3.6 Temperature : 3.7 Used for : 3.8 Maintenance : 4.0 PRESSURE SWITCH : 4.1 Ambient Temperature : 4.2 Terminal Rating : 4.3 Setting Range : 4.4 Overload Capacity : 4.5 Overload Rating(Pressure) :

12 APPENDIX B 0 TESTING SCHEME 1.0 Routine Testing for Solenoid Valves : 1.1 Hydraulic Test for Body Pressure : 1.2 Pick-up Voltage : 1.3 Drop-down Voltage : 1.4 H.V. Test : 2.0 Routine Test for Pressure Switch : 2.1 Pressure withstand : 2.2 H.V. Test at : 2.3 Cut in Pressure(Calibration Range) : 2.4 Cut off Pressure(Calibration Range):