Installation clearance of piston compressors
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What is the control range for the clearance between the piston of a piston compressor and the cylinder head?
3.3.3 Piston and piston rings 3.3.3.1 The surfaces of the piston and piston rings shall be smooth, free from wear, scratches, cracks, deformation, as well as any defects resulting from casting or machining. 3.3.3.2 The piston rings should move freely within the piston grooves and possess a certain degree of expansion force; when pressed by hand, they should be completely seated within the grooves and should be 0.5–1.0 mm lower than the surface of the piston. 3.3.3.3 The installation clearance between the piston and the cylinder shall meet the design requirements, or the value calculated according to the following formula: for cast-iron pistons, it is (0.8～1.2)‰Dmm; for cast-aluminum pistons, it is (1.6～2.4)‰Dmm. (D is the cylinder diameter). 3.3.3.4 The maximum clearance between the piston and cylinder shall meet the design requirements; if no specific value is specified, refer to Table 4. Table 4 Maximum clearance between piston and gas, in mm. Maximum clearance based on cylinder inner diameter: ≤1000: 0.90; >400–450: 3.50; >100–150: 1.20; >450–500: 4.00; >150–200: 1.50; >500–550: 4.50; >200–250: 1.80; >550–600: 4.90; >250–300: 2.20; >600–650: 5.40; >300–350: 2.50; >650–700: 5.90; >350–400: 3.00. 3.3.3.5 The clearance of the piston must meet the design requirements. 3.3.3.6 When installing piston rings, the overlapping sections of adjacent piston rings should be offset by 120°, and they should be placed as far away as possible from the intake port. 3.3.3.7 The piston rings must fit tightly against the cylinder; the outer diameter of the piston rings in contact with the cylinder surface should cover at least 60% of the circumference. There should be no more than two areas where light leaks through, with each such area having an arc length of no more than 45°. The radial gap at these leaky areas should not exceed 0.05 mm. 3.3.3.8 The piston rings and guide rings are placed within the piston, and their thermal expansion gaps (interface gaps and side gaps) shall meet the design requirements; in the absence of specified values, refer to Table 5. Cylinder diameter, assembly clearance, limit clearance, interface clearance, side clearance, interface clearance, side clearance: ≤1000: 0.40, 0.03–0.05; 2.5: 0.15; >100–1500: 0.50, 0.04–0.06; 2.5–3.0: 0.15; >150–2000: 0.80, 0.05–0.07; 3.5: 0.15; >200–250: 1.00, 0.05–0.07; 4.0: 0.20; >250–300: 1.20, 0.06–0.09; 4.5: 0.20; >300–350: 1.40, 0.06–0.09; 5.0: 0.20; >350–400: 1.60, 0.07–0.10; 5.5: 0.20; >400–450: 1.80, 0.07–0.10; 6.0: 0.20; >450–500: 2.00, 0.09–0.12; 6.5: 0.20; >500–550: 2.20, 0.09–0.12; 7.0: 0.20; >550–600: 2.40, 0.09–0.12; 7.5: 0.25; >600–650: 2.60, 0.09–0.12; 8.0: 0.25; >650–700: 2.80, 0.09–0.12; 8.0: 0.25. 3.3.3.9 The thermal expansion clearance for tetrafluoroethylene piston rings and guide rings can be calculated using the following formula. A = (2.8～3.2)%D; S = 0.0lh + H9/d9; B = (0.015～0.018)b. Here, A represents the gap at the interface between the piston ring and the guide ring, in mm ； D — outer diameter of the piston, mm ； S —— Sideways clearance of the piston ring in the piston groove, mm ； h —— Piston ring width, mm ； H9/d9 —— Limit value for clearance fit in the H system, mm ； B – Side clearance of the guide ring, mm ； b—Width of the guide ring, mm. 3.3.3.10 Check the parallelism of the piston rings: place the piston rings flat on a surface, and gently tap around the upper surface of the rings with your finger; there should be no gaps between the ends of the piston rings and the surface.
The view ahead is blocked; Cui Hao’s poem is inscribed above. It has been clearly explained upstairs. The key is to accumulate knowledge and figure it out on your own.
Let me introduce you to the GB50275-98 Code for Construction and Acceptance of Compressor, Fan, and Pump Installation Projects
On the one hand, it is directly related to the cylinder diameter (as shown in the table above), and on the other hand, it is also related to the design requirements of the manufacturer. I think the poster is trying to earn points in order to upgrade, right? Right, hehehe, but it’s better to mention some practical content to get higher scores! ! ! ! ! !
The clearance is generally specified in the compressor’s installation instructions; if not available, it can be determined using relevant standards such as API618.
Where is it? Can it be sent out?
GB50275-98 Code for Construction and Acceptance of Compressor, Fan, and Pump Installation Projects. Available here: http://bbs.hcbbs.com/viewthread.php?tid=7342. Table of Contents: Chapter 1 General Provisions; Chapter 2 Compressors – Section 1 Compressors Delivered as Complete Units; Section 2 Reciprocating Piston Compressors Delivered in Disassembled Form; Section 3 Auxiliary Equipment; Section 4 Commissioning; Section 5 Lubrication-Free Compressors; Section 6 Screw Compressors. Chapter 3 Fans – Section 1 General Provisions; Section 2 Centrifugal Ventilators; Section 3 Axial Flow Fans; Section 4 Roots and Darrieus Blowers; Section 5 Centrifugal Blowers and Centrifugal Compressors. Chapter 4 Pumps – Section 1 General Provisions; Section 2 Centrifugal Pumps; Section 3 Well Pumps; Section 4 Vertical Axial Flow Pumps and Vane-Type Mixed-Flow Pumps; Section 5 Motor-Driven Reciprocating Pumps; Section 6 Steam Reciprocating Pumps; Section 7 Metering Pumps; Section 8 Screw Pumps. Chapter 5 Project Acceptance. Appendix 1 Methods for Measuring Vibration Speed of Fans and Pumps; Appendix 2 Requirements for the Configuration of Suction and Discharge Pipelines for Pumps; Appendix 3 Explanation of Terms Used in This Code. Additional Notes: This post was last edited by Hunter on 2009-2-24 at 11:07
The answer on the 2nd floor was very professional; I admire it
Reply to 1# DJ9089420: Our piston compressors are typically set at 3 mm (2 plus or minus 1). The top dead center is usually slightly higher than the bottom dead center, mainly to account for thermal expansion.