Sample inspection of high pressure cleaning machines
The full process guide to sampling inspection of high pressure cleaning machines
As a commonly used cleaning equipment, the performance, safety and durability of high-pressure cleaning machines directly affect the user experience and safety of use. Sample inspection is a key part of safeguarding product quality and reducing the risk of volume procurement. The five core dimensions need to be developed around sampling scheme formulation, appearance inspection, core performance testing, security compliance verification, and attachment integrity verification to ensure that the sampling sample objectively reflects the quality level of the batch of products.
I. Sampling programming: ensuring sample representation
It is necessary to determine the sample rule according to the batch size, the criterion and the level of risk in order to avoid misjudgment.
1. Reference criteria and sampling ratio
Priority to follow national standards (such as GB / T 37682-2019 "high pressure washing machine") or industry general standards, if there is no clear standard, can be formulated according to the following principles:
Small batch (≤ 50 units): No less than 10% of the sample size, and at least 3 units are sampled (full inspection if the total is ≤ 3 units);
Medium volume (51-200 units): sampling ratio of 8% to 10%, minimum sampling of 5 units;
High volume (> 200 units): 5% -8% sampling ratio, with a minimum sampling of 8 units and a maximum sampling not exceeding 30 units (avoiding excessive testing and cost increases).
2. Sample method
Using random sampling to avoid artificially selecting "quality samples":
Samples are randomly taken from different loading areas and different packaging boxes of the entire batch of goods to ensure that the samples cover "first, middle, final parts" (such as production line batch) or products "at different loading times";
Record the production batch number, factory date, and box number of each sample to facilitate subsequent traceability.
II. Exterior and structural inspection: removal of explicit defects
The appearance is the "first impression" of the product quality, and the structural integrity directly affects the stability of the equipment, which needs to be checked carefully from one desk to another.
1. Exterior details check
Places to Inspect Testing Standards Examples of Common Defects
The fuselage has no scratches, dents or deformation on the surface; The coating is uniform, with no paint peeling, bubbles or color differences; Clarity of marking (brand, model, parameters) Exterior bumps and dents, coating locally peeling, model marking blurred
Interfaces and connectors The screws at the inlet and outlet ports are not damaged, and the seal surface is smooth and free of thorns. The joint is strongly connected to the body and does not loose The screw filament, the seal surface is scratched, the joint shakes
Control panel buttons / knobs are not damaged or jammed; Display screen (if any) clear, no leakage, black screen; Logo and Function Match button broken, display screen flashing, logo error
Cables and plugs The power line is not broken or ageing; The plug pins are not bending or oxidizing; The cable is firmly fixed and does not loose. The external skin of the power line cracks, the plug pins deformation, and the cable falls off
2. Structural stability verification
Handheld / Standing Model: Placed on a horizontal ground, check that the fuselage is smooth and not tilted; The handles, brackets and other components are strongly connected and are not noticeably loose when shaking;
Mobile model (with wheels): When pushing the device, the wheels roll smoothly, without clunks and noisy sound; The braking device (if any) can effectively secure the equipment without failure.
III. Core performance testing: verification of functional effectiveness
The core properties of high-pressure cleaning machines include pressure, flow, power, and operational stability, which need to be tested with professional tools to ensure compliance with product descriptions or standards.
1. Basic parameter testing (essential tools: pressure gauge, flow gauge, power gauge)
Stress tests:
Connect the standard spray gun, start the device and turn it to maximum pressure, measure the actual pressure of the outlet water outlet with a pressure gauge;
Requirements: The deviation between the actual pressure and the nominal pressure does not exceed ± 10% (such as the nominal 20MPa, the actual need is in the range of 18-22MPa);
Test continuously for 5 minutes to see if the pressure is stable and no significant decrease (to rule out pressure leakage due to poor sealing).
Traffic Testing:
Connect a flowmeter at the outlet to record the water output per unit time (usually in L / min);
The deviation between the actual flow rate and the nominal flow rate is no more than ± 5%, and the water flow is even, without the abnormal flow break and splash.
Power Test:
Connect the device to a power meter and measure the actual input power after starting;
Requirements: the actual power and the nominal power (such as 2200W) deviation is not more than ± 15%, and the operation of the power without sharp fluctuations (to avoid motor overload or power virtual standard).
2. Operational Stability and Functional Testing
Continuous operation test: Let the device run continuously for 30 minutes at rated pressure and observe:
Motor operation sound: There is no abnormal noise (such as friction, rumble), and the vibration range is within a reasonable range (handheld machine vibration does not affect grip);
Body temperature: The temperature of the motor casing and pump body does not exceed 60 ° C (detected with an infrared temperature gauge to avoid overheating damage);
Functional switching: If multi-stage pressure regulation is supported, the pressure changes smoothly during the switching, there are no pauses or sudden changes in pressure.
Spitfire / Accessories Features:
Test shot switch: flexible pressure and no leakage after closing;
Replacement of nozzles (e.g. 0 °, 15 °, 40 °): Installation and dismantling are easy, and the flow pattern of different nozzles is in accordance with the design (e. g. 0 0 is direct and 40 ° is fan), and there is no deviation.
IV. Security compliance verification: avoiding use risks
High-pressure cleaning machines are electric tool products, and safety compliance is the bottom line, and we need to focus on verifying whether electrical safety, pressure safety, and protective design meet the standards.
1. Electrical safety testing (key items, according to GB 4706.1-2005 "Safety of household and similar electrical appliances - Part 1")
Insulation resistance test: Measure the insulation resistance between the power line and the body casing with an insulating resistance meter (barometer), not less than 2 MΩ under normal conditions and 0.5 MΩ under hot and humid conditions (to prevent leakage);
Ground resistance test (machine with ground plug only): measure the ground resistance of the ground pins and the metal parts of the body, ≤ 0.1 Ω (ensure the effective grounding and protect personal safety in case of leakage);
Leakage protection (if with leakage protection plug): Simulate leakage situation (such as earth leakage current 10mA), the plug should be within 0.1 seconds tripped, cut off the power.
2. Stress Safety and Protection
Function of mud relief valve: Some models are equipped with mud relief valve (to prevent pipe burst), artificial blockage of outlet to simulate overpressure, mud relief valve should be in the nominal safety pressure (usually 1.2-1.5 times of rated pressure), no abnormal;
Anti-heating / anti-pressure protection: If the temperature of the pumps and water drains (non-holding areas) in operation is high, they need insulation coatings or protective housings; The high-voltage pipeline has no aging, drumming, and no risk of rupture when bent.
V. Annexes and document verification: ensuring integrity
Missing attachments or irregular documents can affect user use, so check the list on a case-by-case basis:
1. Annex integrity
Based on the product packing list, check whether each sample is equipped with the following attachments (depending on the instructions):
Standard accessories: high-pressure water supply pipes, spray guns, common nozzles (3-4), inlet filter connectors, power cords;
Optional accessories: extension rod, rotating brush head, foam pot, instruction manual / warranty card;
Requirements: Accessories are non-damaged, in full quantity, and compatible with the body model (e.g. nozzle caliber meets pressure requirements).
2. Document Prescriptiveness
Check whether each product comes with a Chinese instruction manual (imported products must have a Chinese version), which should include product parameters, use, safety warnings, maintenance, troubleshooting;
The warranty card needs to have the official stamp of the manufacturer, the date of production, and the information is consistent with the body marking.
It is prohibited to appear in cases such as "no instructions," "the contents of the instructions are inconsistent with the product," and "instructions only in foreign languages."
VI. DETERMINATION AND PROCESSING OF CHECKING RESULTS
Qualifying criteria:
The appearance, performance, safety and accessories of all sampled samples conform to the requirements and are free from fatal defects (such as leakage or severe substandard pressure);
If there is a minor defect (such as a small scratch on the casing that does not affect the function), the defect rate needs to be ≤ 10% (if 10 units are sampled, up to 1 units have a minor deficiency).
Unqualified judgement:
Fatal defects (e.g., leakage, inability of the motor to start, pressure deviation of more than 30%) occur, regardless of the number, and the whole is judged to be inadequate;
If the slight defect rate is > 10%, or the main performance (e.g. pressure, flow) does not meet the standard number of tables > 20%, the whole is determined to be unqualified.
Substandard handling:
Require the manufacturer to rectify within a deadline and to resample the product after rectification;
If after rectification, the shipment remains substandard, you may refuse to receive it, request a return, or replace the batch.
Document the inspection report (including sample information, test data, photographs of defects) as a basis for communication with the manufacturer.
VII. PRECAUTIONS
Testing environment: Ensure that the testing site is well ventilated and has a stable power supply (220V / 380V according to equipment requirements) and avoid testing in a humid, dust-laden environment (affecting electrical safety test results);
Safety of personnel: When testing high-pressure pipelines, wear protective gloves and goggles to avoid direct water exposure to the human body. It is prohibited to touch the high temperature parts of the motor during the operation of the equipment;
Tool calibration: Pressure gauges, flowmeters, and power gauges need to be calibrated in advance (within the validity period) to avoid inaccurate test results due to tool errors.
Through the above systematic sampling inspection process, high-pressure cleaning machines of acceptable quality can be effectively screened out, reducing the risk of volume procurement, and ensuring the safety and stability in subsequent use.