1. Visual inspection standards and inspection methods:
Class A surface: an external surface that can be viewed directly, such as the front and front sides of an electric water heater, hereinafter referred to as the A surface.
Class B surface: Inconspicuous external surfaces, such as the rear and rear surfaces of electric water heaters, hereinafter referred to as the B surface.
Class C surface; internal and external surfaces that are not easily visible, such as the floor surface of electric hot water, hereinafter referred to as the C surface.
Luminosity: Normal light or 200-300LX (equivalent to a distance of 750mm for a 40W fluorescent lamp) The inspection surface of the product should be approximately 45 ° from the visual direction of the inspector.
The distance between the inspector’s visual direction and the surface of the product to be inspected is as follows:
A surface: 400MM B surface: 500MM C surface: 800MM
Degree of defect
Basic method for judging the degree of surface defects: under a standard inspection light source, the distance from the observation object is 400mm, and it should be at an angle of 45 degrees with the observation surface. Defects that are not visible at a glance are slight defects, visible at a glance, but not very obvious, are general defects. Visible and obvious defects are serious defects, and defects that are visible at a glance and seriously affect the appearance are fatal defects.
Appearance is based on 1dm2. The 11.3cm circle selects the most defects.
Inspection methods and inspection standards
The A side should be smooth and flat with no obvious defects. No serious defects are allowed. No hand-painting is allowed to repair defects. Minor defects are allowed. No rough feeling or deformation can be felt by hand. The insignificant general defects have a diameter greater than 1mm is not allowed, less than 1mm is not allowed to exceed 10 points, and the concentration is not more than 3 / cm2. For non-orthographic planes, the standard can be appropriately relaxed. In the detection area, the diameter is less than 1mm. It is not allowed to exceed 15 points, and the concentration is not more than 3 / cm2.
The B surface should be smooth and smooth without obvious defects. No serious defects are allowed. Minor defects are allowed, and there is no rough feeling or severe deformation when touched by hand. Non-obvious general defects are not allowed in the detection area with a diameter greater than 1.2mm and less than 1.2. mm is not allowed to exceed 20 points, and the concentration is not to exceed 3 / cm2. For non-orthographic planes, the standard can be appropriately relaxed. In the detection area, the diameter is less than 1.2mm. It is not allowed to exceed 30 points, and the concentration is not more than 3 / cm2.
The C-plane allows the presence of general defects and serious defects that do not affect the appearance quality. The splicing gap is less than 1mm, which is acceptable. If it is more than 1mm but less than 1.5mm, it can be conceded according to the actual situation, and more than 1.5mm is unacceptable.
Signs, stickers, print inspections
Check the position of the signs, logos, stickers, and silk screens in accordance with the technical data to check that they are accurate, flat, and free from obvious skew. Failed.
Inlet and outlet pipe inspection
Check the water inlet and outlet pipes. The mouth of the pipe should be smooth and smooth, and the wire teeth should not be damaged and no obvious skew. Meet the requirements as qualified, otherwise as unqualified.
The exposed length of the inlet and outlet pipes should meet the design requirements. The length of the inlet and outlet water pipes shall meet the design requirements.
2. Structural parameter inspection standards and inspection methods
The overall dimensions of the product and the dimensions of the packaging box need to meet the dimensions and tolerance requirements of the design drawings, and those without tolerances are implemented as free tolerances.
Inspection with external dimensions
The size of the external fit must meet the size and tolerance requirements of the design drawing, and the free tolerance is implemented if no tolerance is marked. The outer cymbal fittings should be free from obvious skew.
Content volume inspection
Fill the container with water, put it on the weighing scale using a measuring bucket, and gradually pour the water from the product into the measuring bucket, and finally get the total water storage. The minimum content should meet the relevant capacity standards of the country or country of use, or the minimum allowable capacity requirements confirmed by the customer.
3. Inspection standards and inspection methods for hidden structural parameters
Quality inspection of slush layer
Use the light method to check the quality of the inner slush layer. The surface of the slush layer should be milky white, and there should be no burnt black, scars, cracks, whitening, puncture points, and debris in the slush layer. qualified.
Use light reflection perspective inspection or thickness gauge to check the thickness of the slush layer. The light reflection perspective inspection of the surface of the slush layer should show a uniform milky white, and there should be no gray-black shadows of the perspective substrate color (indicating that the slush layer is too thin). The minimum thickness measured by the thickness gauge should be more than 1.5mm, otherwise it is unqualified.
Foam layer thickness inspection
Using the thickness probe, take a point from the appearance and insert it into the shell to contact the liner, and measure the thickness of the foamed layer in each part. The thickness of the foamed layer should meet the design requirements. Those who meet the design requirements are qualified. If the area does not meet the design requirements but the area does not exceed 10%, and the error does not exceed 2mm, it may be conceded in consideration of the actual situation, otherwise it is unqualified.
Foam layer density test
Take a piece of 50X50X40 foam from both ends and the middle of the product, cut off the outer skin layer, and measure the density of the sample to calculate the average density. The average density should meet the designed density requirement, and the lowest density sample density must meet the minimum density requirement. Otherwise it is disqualified. The normal density requirement is 32 ~ 38KG / M3.
The products are connected into a system by using standard external connection accessories, and the normal work is performed under the use conditions. There must be no leakage at any connection parts, otherwise it is unqualified.
The inner tank is tested in accordance with the tightness test method, and there should be no leakage or leakage, otherwise it is unqualified.
4. Electrical safety performance inspection standards and inspection methods
4.1 Inspection of circuits and electrical components
Circuit and electrical device inspection
The electrical components are installed correctly, especially the switches, thermostats, and wiring cannot be reversed, incorrectly connected, or incorrectly connected. The installation of electrical components must be safe and reliable. Under the condition of limited pulling, pushing and pulling, the live parts of electrical components should not touch the metal parts such as the inner liner, screws, or heating parts. Cause the connection cable to be too tight.
There must be no foam, adhesive tape, screws, or metal parts spilling from the end cap.
The wiring and cable ties must be neat and reasonable. The connecting wires must not touch the sharp angles. The connecting pipes of the thermostat and temperature limiter probes must not be flattened.
Safety distance inspection of electrical components
Check that the distance between all exposed wires and terminals and metal parts should exceed the minimum distance required by safety regulations. All connecting wires and accessories should be firmly fixed. Under shaking and slight force, the distance from metal parts should still exceed the minimum safety distance. .
Ground wire safety connection check
The ground wire should be connected with standard yellow-green wires, and the connection fittings should be made of copper. The connection should be firm and reliable and should not be loose. Ground line signs, L, N and other signs must be correct, clear and durable;
Circuit connector safety test
Shake and pull the terminals and wires by hand, and the terminals, wires and screws should not loosen or fall off.
Check whether the switch, indicator light and temperature control can work and indicate normally.
The knob must be flexible, smooth, and pointed correctly; the switches and keys are correct and reliable;
Accessories stability check
Use one hand to hold the case where the power cord enters, and hold the power cord with the other hand, and push it in and out twice. The power cord must not go in or out more than 2mm, and the power cord cannot be hung or broken. When it is pulled off, the screws holding the wire clamp must not be loose;
4.2 Ground resistance test
Ground resistance test
Insert the plug of the electric water heater into the socket of the ground resistance tester, and then clamp the ground wire clip to the water nozzle of the electric water heater or the hanger without spraying, start the ground resistance tester, and read the resistance value is not greater than 0.1 ohm (100 millimeters) (Europe) is qualified, otherwise it is disqualified.
The standard for grounding resistance is 25A 5S not more than 0.1 ohm (100 milliohms).
4.3 Withstand voltage test
Plug the electric water heater with a qualified grounding resistance into the socket of the withstand voltage tester, press the reset button of the leakage protection switch, adjust the switch and the thermostat to the on state, and start the withstand voltage tester without breakdown or flicker. To be qualified, breakdown, flashing, arc flash, and smoke were unqualified. The standard of withstand voltage is 1800VAC 5S without breakdown and flicker.
Note: During the pressure test, never touch the metal part of the water heater!
4.4 Leakage current test
Leakage current test
Press the reset button of the leakage protection switch of the electric water heater that has passed the withstand voltage test, adjust the switch and the thermostat to the on state, insert the plug of the electric water heater into the socket of the leakage current tester, and dial the L, N switch, read out the leakage current value in the L and N states, the leakage current per kilowatt is less than 0.75mA is qualified, otherwise it is unqualified.
The leakage current standard is 233VAC 5S leakage value <0.75mA / KW. Our company requires that the leakage current standard of each electric water heater is 233VAC 5S leakage value <0.75mA.
When testing the leakage current, check whether the switches and indicators can be lit and correct. Note: When testing the leakage current, the metal part of the water heater is live!
4.5 Power test
Insert the water heater plug that passed the leakage current test into the socket of the electrical parameter tester, turn on each switch one by one, and read out the corresponding power. The measured power is 0.9 ~ 1.05 times the rated power is qualified, otherwise it is unqualified.
4.6 Functional test
Use heating according to the normal use state, check whether the temperature controller is normal, whether the switch is normal, whether the indicator light is normal, whether the inner tank water is normal heating, short the temperature controller, and check whether the temperature limiter can work normally. Everything is normal, otherwise it is unqualified.
5. Other inspection items
Stress safety test
Use an external air source to pressurize the tank filled with water to the take-off pressure of the safety valve, and check whether the safety valve takes off normally. When the pressure of the inner tank reaches the rated pressure of the safety valve, the normal pressure of the safety valve is qualified and abnormal. Failed.
Inject the liner into 90% water, then immerse the liner into the pool, increase the liner pressure to twice the use pressure, stabilize the pressure for 10 minutes, and observe whether the liner has changed. After the pressure was released from the liner, the shape was qualified if it did not change, and the shape appeared deformed and distorted, and even failed.
Liner fatigue test
Connect the bladder to the fatigue tester, and perform the pressure and pressure fatigue test. The frequency setting and frequency are performed according to the relevant product technical requirements. After the fatigue test is completed, the bladder is qualified if there is no obvious deformation and leakage. After the fatigue test is completed, In the case, obvious deformation and leakage of the inner liner were unacceptable.
Thermal insulation test
Warm the water in the product to the set temperature, turn off the heating power, place it naturally for 24 hours in a standard environment, measure the temperature to reduce the temperature difference, calculate the insulation performance parameters, and meet the relevant requirements of the country and the country of use as qualified, otherwise it is unqualified .
Thermal yield detection
The product is warmed up to the set maximum temperature. After reaching the temperature, it stays stable for 10 minutes. Measure the temperature of the water and then close the water inlet valve. Pour the hot water in the machine into the insulation bucket and mix it uniformly. Measure the temperature after mixing. And the temperature after mixing, calculate the heating rate of the liner water.
The product is heated from the set temperature to the set maximum temperature. After reaching the temperature, it stays stable for 10 minutes. Turn off the power, use a 45-degree thermostatic valve to drain water into the measuring barrel, and keep it until the outlet temperature is lower than 42 degrees. The amount of water and product content were used to calculate the thermal yield.
Suspension strength test
Fill the product with water and hang it on the suspension test wall, and then use the weighting block to double the weight of the product and suspend it for 4 hours. Check whether there is deformation in the hanger and the shell. Damage is qualified, otherwise it is unqualified.
Put the product in a -30 degree freezer, store it for 12 hours, take it out to restore the temperature at ambient temperature, and check whether the shell is deformed or broken. If there is no obvious deformation and crack, it is qualified, otherwise it is unqualified. Then test whether the product can still work normally, it can work normally and the electrical performance test is qualified, otherwise it is unqualified.