Today, solid wood composite flooring (three-layer, multi-layer solid wood composite floor) is gradually being loved by consumers, but how to choose is the current concern of consumers.
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First, the intrinsic quality of parquet
Intrinsic quality is a key indicator of solid wood composite flooring, but it is difficult to determine with certainty and must pass inspection methods. Therefore, the inspection report must be viewed. The content is as follows:
1, formaldehyde release of solid wood flooring
The problem is that the glued floor made of urea-formaldehyde resin glue has a problem that if the amount of formaldehyde released into the air is too large, it will be harmful to the human body.
China has stipulated that the concentration of formaldehyde in the air of public places must not exceed 0.12 milligrams per square meter.
If, during the laying process, a more pungent smell of formaldehyde has been detected, the concentration of formaldehyde in the air has exceeded the standard.
For the determination of the formaldehyde concentration of solid wood flooring, the perforated extraction method is currently used in China.
The resulting "perforation value" represents the amount of releasable formaldehyde contained in a 100 gram product.
If the "Punch Road" is about 9 milligrams per square meter or less, it can basically meet the national environmental protection standards for formaldehyde concentration.
If less than 30 milligrams per square meter, generally meet the B class technical standards.
2, the moisture content of solid wood flooring
The moisture content is usually about 12% basically qualified (different from area to area, and different moisture content standards are implemented).
3, solid wood composite flooring adhesive properties
Solid wood composite flooring is manufactured by hot-pressing the surface of the adhesive-coated board. Therefore, the glue quality directly affects the use effect and the service life.
The quality of gluing can be reflected by two performance indicators, namely impregnation and gluing strength.
The determination of these two indicators is to place the test piece in water with a certain temperature after treatment. The lower the impregnation value, the better. The higher the bond strength, the better.
The quality of solid wood flooring is mainly considered from the following aspects:
Second, the appearance of solid wood flooring
Observe the surface of solid wood flooring:
1, the surface paint brushing gloss, paint film is full and even, with or without pin particles, with or without indentation, planing marks.
2, indicating that the material has no obvious defects. The surface of the wooden floor should not have rot, dead knots, knot holes, wormholes, cracks, clips and other defects.
3, the surrounding ripples, grooves complete.
Third, solid wood flooring size tolerances meet the requirements
1. Whether the length, width and thickness of solid wood composite flooring are the same as the product introduction;
2. Whether the parquet and size mosaic of the solid wood flooring are tight and flat can be assembled by spot-checking multiple floors and assembling on a flat glass table or floor, and checking the degree of tightness of the composite flooring and whether the surface is smooth or not.
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A ball check valve is a check valve in which the closing member, the movable part to block the flow, is a spherical ball. In some ball check Valves, the ball is spring-loaded to help keep it shut. For those designs without a spring, reverse flow is required to move the ball toward the seat and create a seal. The interior surface of the main seats of ball check valves are more or less conically-tapered to guide the ball into the seat and form a positive seal when stopping reverse flow.
Ball check valves are often very small, simple, and cheap. They are commonly used in liquid or gel minipump dispenser spigots, spray devices, some rubber bulbs for pumping air, etc., manual air pumps and some other pumps, and refillable dispensing syringes. Although the balls are most often made of metal, they can be made of other materials, or in some specialized cases out of artificial ruby. High pressure HPLC pumps and similar applications commonly use small inlet and outlet ball check valves with both balls and seats made of artificial ruby, for both hardness and chemical resistance. After prolonged use, such check valves can eventually wear out or the seat can develop a crack, requiring replacement. Therefore, such valves are made to be replaceable, sometimes placed in a small plastic body tightly-fitted inside a metal fitting which can withstand high pressure and which is screwed into the pump head.
There are similar check valves where the disc is not a ball, but some other shape, such as a poppet energized by a spring. Ball check valves should not be confused with Ball Valves, which is a different type of valve in which a ball acts as a controllable rotor to stop or direct flow.
A diaphragm check valve uses a flexing rubber diaphragm positioned to create a normally-closed valve. Pressure on the upstream side must be greater than the pressure on the downstream side by a certain amount, known as the pressure differential, for the check valve to open allowing flow. Once positive pressure stops, the diaphragm automatically flexes back to its original closed position.
A swing check valve or tilting disc check valve is check valve in which the disc, the movable part to block the flow, swings on a hinge or trunnion, either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section may be perpendicular to the centerline between the two ports or at an angle. Although swing check valves can come in various sizes, large check valves are often swing check valves. The flapper valve in a flush-toilet mechanism is an example of this type of valve. Tank pressure holding it closed is overcome by manual lift of the flapper. It then remains open until the tank Drains and the flapper falls due to gravity. Another variation of this mechanism is the clapper valve, used in applications such firefighting and fire life safety systems. A hinged gate only remains open in the inflowing direction. The clapper valve often also has a spring that keeps the gate shut when there is no forward pressure. Another example is the backwater valve (for sanitary drainage system) that protects against flooding caused by return flow of sewage waters. Such risk occurs most often in sanitary drainage systems connected to combined sewerage systems and in rainwater drainage systems. It may be caused by intense rainfall, thaw or flood.
A stop-check valve is a check valve with override control to stop flow regardless of flow direction or pressure. In addition to closing in response to backflow or insufficient forward pressure (normal check-valve behavior), it can also be deliberately shut by an external mechanism, thereby preventing any flow regardless of forward pressure.
A lift-check valve is a check valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly. When the pressure is no longer higher, gravity or higher downstream pressure will cause the disc to lower onto its seat, shutting the valve to stop reverse flow.
An in-line check valve is a check valve similar to the lift check valve. However, this valve generally has a spring that will 'lift' when there is pressure on the upstream side of the valve. The pressure needed on the upstream side of the valve to overcome the spring tension is called the 'cracking pressure'. When the pressure going through the valve goes below the cracking pressure, the spring will close the valve to prevent back-flow in the process.
A duckbill valve is a check valve in which flow proceeds through a soft tube that protrudes into the downstream side. Back-pressure collapses this tube, cutting off flow.
A pneumatic non-return valve.
Multiple check valves can be connected in series. For example, a double check valve is often used as a backflow prevention device to keep potentially contaminated water from siphoning back into municipal water supply lines. There are also double ball check valves in which there are two ball/seat combinations sequentially in the same body to ensure positive leak-tight shutoff when blocking reverse flow; and piston check valves, wafer check valves, and ball-and-cone check valves.
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