PW-1 Rapid water content tester for sand/ Sand moisture tester

The main parameters
1. Designed measurement temperature: 20±5℃
2. Maximum design pressure: 4Mpa
3. Maximum working pressure: 0.3mpa
4. Air tightness test pressure: 0.4mpa
5. Weight of measured material: 30g
6. Weighing water content range: 0-30%
7. Energy range of proportional method: 0-85%

Brief description of the product
By the Beijing Institute of Construction Engineering trial-produced by the completion of the sand water-bearing rapid tester, should be the construction site, concrete prefabrication plant, commercial concrete mixing plant and civil construction laboratory and other units for the construction of sand water rate rapid determination of the need to develop. The absolute error is less than 0.5% compared with the current test methods, the instrument is reliable in testing principle, instrument is small in size, light weight to carry easy to use, does not need any power supply, short test time (2 ~ 3 minutes), time saving, energy saving, save cost advantages.
The instrument has been applied for national patent and passed the technical appraisal organized by Beijing Municipal Commission of Urban and Rural Construction on October 27, 1989.

Instrument usage (Operating Procedure)
1. Clean the instrument
Clean the inside and outside of the instrument with a brush to ensure that there are no items stored in the instrument.
2. Preparation of test samples
A number of representative sand samples (- 100 g or so) were taken for the test.
3. Weigh sand samples
Test with the weight of the sample is usually depends on the size of the original sand moisture content, moisture content is small, the sample can be more, moisture content of samples can be less, in normal conditions, sample weight it is advisable to take 5 grams, when the weight of the sand and the mathematical model of the required weight from the conversion process to deal with the test result, see the meter for example, weighing scales are t should not be greater than 100 mg.
4. Add sand sample
Place the weighed sand sample into the sampler, place the sand sample at the bottom of the instrument, and then place the instrument upside down.
5. Add hygroscopic agent
The weight of the hygroscopic agent is equal to the weight of the sand sample. Place the quantified hygroscopic agent near the mouth of the instrument. At this time, attention should be paid to prevent the sand sample from contacting the hygroscopic agent before closing the instrument.
6. Turn off the instrument
Keep instrument flat, tighten upper cover and close bleed valve.
7. mixed
Stand up the instrument and gently shake the sand sample to mix well with the hygroscopic agent, shaking it repeatedly for one to two minutes.
8. reading
When the pressure pointer does not move, put down the instrument to make the gas in the instrument level off. Then look up at the pressure display, read the pressure value accurately to 0.0005MPa.
P= (P1+P2) 12
“(0.0530+0.0525) 12
=0.0538 (MPa)
The applicable condition of the equation is the sand sample weight S grams, the following conversion should be made:
1/5-3 reduced pressure P’ =P/3=0.0146 (MPa)
Generation into the formula: W=85.73 x 0.0146-0.17 =2.54%
2.54
W (dry)= 100-2.54 X 100=2.61
Or table lookup (P= 0.0146mpa)

Matters needing attention
When using this instrument, the following points should be noted:
1. Strictly follow each operating procedure
2. A small amount of flammable gas will be generated during the test, so fire prevention should be paid attention to. Open fire is strictly prohibited in the test site.
3. The maximum test pressure should be less than 0.12mpa; otherwise, open air valve should be used.
4. After the test, open the air valve slowly to let out the gas. Don’t put the air vent right to your eyes.
5. Only the permitted materials can be tested (construction sand with moisture content within 15%), and other materials can be used only with the approval of the developer.
6. Each hygroscopic agent = a kind of high-efficient water absorbing material, which should be kept dry and moistureproof during storage
7. Direct contact with the skin is strictly forbidden. In case of contact with the skin accidentally, brush it off with a hairbrush before filling the hospital with plenty of water.
8. The instrument should be checked regularly to ensure its test accuracy & LT;0.98
9. Vent the air and clean the instrument
Open the bleed valve first, open the upper cover after the pressure pointer returns to zero, pour away the reactants, and clean the instrument with a brush for the next use.
10.Calculate or look up tables
The arithmetic mean value of the two pressure values tested in parallel is taken and substituted into the following equation to obtain the wet base water content of the measured second sample. If the accuracy is not high, the wet base water content of the sand sample can also be obtained directly from the pressure value in the table.
W=185.73P-0.17
In the equation:
W – Moisture content of wet base of sand sample(%)
B – Gas pressure(MPa)
Applicable conditions: sand sample weight 5 grams
If it needs to be converted into dry base moisture content, it can be calculated according to the following formula:
W(wet)
W干= 100*W(wet) x100%
In the equation:
W(dry) – Dry base moisture content of sand sample
W(wet) – Wet base moisture content of sand sample
water weight
W(dry)= wet sand weight -water weight X 100%
water weight
W(wet)= wet sand weight X 100%

Calculation example
1.Given a concrete project at a certain construction site, in order to carry out the concrete mix ratio conversion on site, it is necessary to know the moisture content of sand used. PW I sand seed water-bearing tester was used for rapid determination, and the result of two parallel measurements were P.= 0.0450mpa and P:=0.0475MPa.
Calculate the moisture content of the sand (sand sample weight 5 grams, hygroscopic agent weight 5 grams).
Solution: Average the results of the two measurements
p= (P.+P:) /2= (0.0450+0.0475) /2=0.0463 (MPa)
Generation into the formula:
W=185.73 x 0.0463-0.17=8.43%
8.43
W(dry)= 100-8.43 X 100%
Or look up the table for, P=0.0463=0.075 (MPa) ,W=-13.76%
2.The water content of sand used in a construction site was measured by PW-I sand water-bearing tester. The test conditions were as follows: the weight of sand sample was 15g, the weight of hygroscopic agent was IS, and the results were P= 0.0530mpa, P-=0.052SMPa.
Solution: The average of the two test results:
Size（mm）:340*270*130
Weight（kg）:3.5kg