**1. Scope** This engineering specification outlines the minimum requirements for metering pumps used in industrial installations, including their drivers and auxiliary equipment. It covers the performance, structural design, materials, drive systems, testing procedures, labeling, packaging, and procurement aspects of metering pumps. The document ensures that all components meet industry standards and are suitable for long-term, reliable operation under specified conditions. **2. Standards, Specifications, and Regulations** 2.1 In addition to the technical specifications outlined in this document, the following standards shall apply: - GB 9236: Technical Conditions for Metering Pumps - GB 7783: Test Methods for Metering Pumps - API 675: Positive Displacement Pumps – Controlled Volume 2.2 In case of conflict between the engineering specifications and the referenced standards, the engineering provisions shall take precedence. The seller must inform the buyer in writing about any discrepancies, ensuring that the buyer is aware and can resolve them accordingly. **3. General Rules** 3.1 Unless otherwise specified, pumps, drives, and their auxiliary equipment must be suitable for outdoor installation and continuous operation at both the minimum and maximum ambient temperatures. The continuous operating cycle should not be less than 8,000 hours. 3.2 Prototype units that have not been tested cannot be accepted. Only production units that have demonstrated at least two years of safe operation under similar conditions are acceptable. 3.3 Unless otherwise stated, the seller must provide the complete pump system, including the pump, coupling, driver, and all necessary auxiliary equipment, and ensure the quality of the entire unit. 3.4 Unless otherwise specified, the pump, driver, coupling, shroud, and auxiliary equipment should be mounted on a single base to ensure stability and ease of installation. **4. Performance** 4.1 The metering pump must be capable of flow regulation with an adjustable ratio of at least 10:1 (i.e., from 10% to 100% of the rated flow). The accuracy of metering between 25% and 100% of the rated flow should be within ±1%, while linearity and repeatability should be within ±3%. 4.2 The scale or handwheel adjustment must have an accuracy higher than ±0.1% of the indicated value. 4.3 The dosing pump must have a nominal flow rate of at least 110% of the maximum flow rate specified by the user. 4.4 The motor’s rated power should be at least equal to K times the maximum shaft power of the metering pump, including gear box and coupling losses. The K value is determined as follows: | Maximum Shaft Power (kW) | K Value | |--------------------------|---------| | Pa ≤ 19 | 125% | | 19 < Pa ≤ 55 | 115% | | Pa > 55 | 110% | 4.5 The NPSHa and NPSHr must be referenced to the same surface. If the difference between NPSHa and NPSHr is less than or equal to 0.6 m, a NPSH check must be performed. **5. Structural Design** 5.1 Pressure Parts 5.1.1 The maximum permissible outlet pressure of the pump must be at least 110% of the rated outlet pressure. 5.1.2 All pressure parts, including areas affected by inlet pressure, must be designed for the maximum outlet pressure and temperature. The allowable stress values for materials must not exceed: - For domestic pumps: HG20531-93 (for cast iron and steel containers) - For imported pumps: ASME Section VIII 5.2 Interfaces 5.2.1 Unless otherwise specified, all interfaces must be flanged. 5.2.2 Domestic pump flanges must comply with GB9112, while imported pumps must follow ANSI B16.1 and B16.5. Flanges with larger diameters or thicknesses are also acceptable. 5.2.3 Inlet and outlet flanges must be of the same pressure class. 5.3 Piston Pump 5.3.1 The stuffing box must include a packing ring for flushing or lubrication. 5.3.2 The liquid end packing seal must prevent leakage from entering the power side. 5.4 Diaphragm Pump 5.4.1 Single or double diaphragm pumps must be equipped with first-limit agencies. 5.4.2 Double-diaphragm pumps must be filled with inert fluid on both sides of the diaphragm, and a rupture detection probe must be installed. 5.5 Bearings Bearings must be standard type; non-standard bearings are not permitted. 5.6 Buffer If specified, the seller must provide inlet and outlet buffers, and the type must be agreed upon with the buyer. 5.7 Safety Valve 5.7.1 The oil relief valve on a diaphragm pump must be self-resetting, adjustable, and easily replaceable, with a set pressure of at least 110% of the pump’s rated pressure. 5.7.2 An external relief valve must be provided for plunger pumps if specified on the data sheet. 5.8 Auxiliary Piping 5.8.1 If lubrication, cooling, or sealing flush systems are required, the seller must provide and install them on the pump or base. 5.8.2 All piping systems must have a wall thickness of at least 1.6 mm (1/16 in.) and a minimum diameter of 1/2 in. (13 mm). 5.8.3 Pipe fittings of 1-1/4 (32 mm), 3-1/2 (90 mm), 7 (175 mm), and 9 (225 mm) inches are not allowed unless otherwise specified. **6. Materials** 6.1 The purchaser must specify the materials on the pump data sheet. If the seller proposes alternative materials, they must submit a written report for the buyer’s approval. 6.2 Unless otherwise stated, carbon steel and low-alloy steel should have a corrosion margin of 3 mm, while high-alloy steel requires no margin. 6.3 Asbestos-containing fibers are strictly prohibited. 6.4 Rubber materials must not be used for transporting organic solvents. 6.5 Cast iron must not be used for conveying flammable, explosive, or toxic media. 6.6 Except for austenitic stainless steel, the seller must perform V-notch impact tests on base metals and weld joints when the medium or ambient temperature is ≤ -20°C. **7. Shop Testing** 7.1 The shop test project must be based on the pump data sheet. 7.2 A hydrostatic test at 1.5 times the maximum allowable working pressure (but not less than 0.14 MPaG) is mandatory. Stability accuracy must be within ±1%, and repeatability and linearity tests are optional with a precision of ±3%. 7.3 If the buyer needs to be present during testing, the seller must notify the buyer at least 20 days in advance. 7.4 Non-visual test results must be documented and submitted for the buyer’s approval. **8. Painting, Marking, and Packaging** 8.1 Painting 8.1.1 All surfaces must be cleaned of dust, rust, and oil before painting. 8.1.2 The topcoat color must be chosen according to the buyer’s request. 8.2 Marking 8.2.1 The pump nameplate must be made of 18-8 stainless steel and securely attached to a visible location. 8.2.2 The nameplate must include: - Device name / model - Seller’s name and trademark - Pump model and name - Main parameters (rated flow, max outlet pressure, relief valve setting, shaft power, weight) - Serial number and date of manufacture 8.3 Inlet and outlet ports must be sealed with metal plates, rubber gaskets, and at least four bolts. 8.4 The pump and its auxiliary piping (including driver and accessories) must be packaged to prevent damage during transport and remain protected for at least six months. **9. Documents, Drawings, and Information** 9.1 Vendor Offer Information The seller’s offer must include: - Completed data sheet with full seller information - Preliminary dimensions and piping layout - Requirements for utilities (water, electricity, steam) - Typical pump profile - Recommended spare parts list - Compliance with specific instructions; if not met, a detailed discrepancy list must be provided. 9.2 Contract Information 9.2.1 The seller must deliver documents as specified in the purchase order, including the correct number of copies and delivery address. 9.2.2 Each document page must be marked with: - Buyer’s company name - Project number - Purchase order number or file number - Pump number - Any additional notes from the purchase order 9.2.3 The seller must provide at least the following documents: - Document list - Pump data sheet - Stability accuracy test report - Dimensions and layout (including main inlet/outlet locations, pressure ratings, electrical junction box, and allowed forces/torques) - Auxiliary piping layout and connection table - Pump section view with part material list - Sealing profile with part material list - Spare parts list - Lubricant and hydraulic oil list - Auxiliary equipment data sheet (if applicable) - Installation, maintenance, and operation manual 9.2.4 The seller must also provide any requested reports, such as: - Material test reports - Reproducibility and linearity test reports - Factory test data records - Other required test reports

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