Cleanroom cleanliness and microbial measurement methods

Cleanliness determination

1.The construction acceptance specification JGJ71 stipulates as follows

a. The minimum number of sampling points is shown n the table below, and each measuring point is sampled at least 3 times.

area（m2）

Cleanliness

Level 100 and above

1000

10000

100000

Less than 10

2~ 3

100

200

400

160

126

1000

400

316

100

2000

800

633

200

b. The minimum sampling volume for cleanliness determination is as follows:

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Cleanliness level (level)	^{Particle size (mm)}
Cleanliness level (level)	0.1	0.2	0.3	0.5	5.0
1	17	85	198	566
10	2.83	8.5	19.8	56.6
100		2.83	2.83	5.66
1000				2.83	85
10000				2.83	8.5
100000				2.83	2.83

c. For unidirectional cleanrooms, the sampling port should face the direction of the airflow. For non-unidirectional cleanrooms, the sampling port should face upward. The sampling speed should be as close to the indoor airflow speed as possible. That is (constant speed sampling).

Principle of measurement point arrangement: no less than 5 measurement points per layer, and layered arrangement can be used when there are more than 5 points. The measurement points are arranged on the diagonal line 0.8m above the ground.

2.Determination of cleanliness measurement results

If the measured state (empty, static, dynamic) is the same as the state agreed in advance, the upper limit of its cleanliness level is used as the evaluation standard. If the measured state is empty or static, the number of particles in the dynamic state will definitely be high. Sometimes 5 to 10 times the number of particles in the empty state can be used to estimate the number of dust particles in the dynamic state.

Determination of microbial particles

1. Arrangement and requirements of sampling points

a. When measuring floating bacteria, the location of the sampling point can be the same as the arrangement of the floating particle measurement point. The measurement point is 0.8 to 1.5m from the ground, and the air outlet measurement point is about 30cm away from the air supply surface. Measuring points can be added at key locations as needed, and the measuring points should be evenly arranged. See the table below:

Area（m2）	Cleanliness
	100		10000		100000
	verify	moniter	verify	moniter		verify	monitor

Less than 10	2~3	1	2	1	2
10~20	4	2	2	1	2
20~40	8	3	2	1	2
40~100	16	4	4	1	2
100~200	40		10		3
200~400	80		20		6
400	160		40		13

b. When measuring sedimentation bacteria, the sampling point location can be arranged in the same way as the suspended particle measurement point. The measurement point is 0.8~1.5m from the ground. Measuring points can be added at key locations as needed. The measurement points should be arranged evenly. For the sedimentation bacteria method, not only the minimum total number of samples must be met, but also the minimum number of sampling culture dishes must be met. See the table below:

area（m2）	^Cleanliness
area（m2）	100	10000	100000
Less than 10	2~ 3	2	2
10~20	4	2	2
20~40	8	2	2
40~100	16	4	2
100~200	40	10	3
200~400	80	20	6
400~1000	160	40	13
1000~2000	400	100	32
2000 and above	800	200	63

Cleanliness level (grade)	90 culture blood count (calculated based on sedimentation for 0.5h)
above 100	44
100	14
1000	5
10000	2
100000	2

Cleanliness level	level	Sampling volume/times
Cleanliness level	level	Daily monitoring	Environmental Verification
100		600	1000

10000		400	500
100000		50	100

2.Method for determination of microbial particles

a. Determination of floating bacteria

First, the measuring instruments, culture dishes, samplers, etc. must be disinfected and sterilized. The sampling port and sampling tube must be sterilized at high temperature before use. Second, the sampler should wear clean clothes corresponding to the clean room level. Before placing or replacing the culture dish, both hands should be disinfected with disinfectant. Third, after the instrument is disinfected and before placing the culture dish, start the vacuum pump to exhaust air to evaporate the residual disinfectant in the instrument for no less than 5 minutes. Fourth, turn off the vacuum pump, put in the culture dish, cover the lid and adjust the sampler.

Fifth, place the sampling port at the sampling point, turn on the sampler and vacuum pump in turn, turn on the timer and select the sampling time according to the sampling amount. Sixth, after the sampling is completed, place the culture dish in a constant temperature incubator at 30~50oC for no less than 48 hours. Seventh, count with the naked eye, and then use a 5~10 times magnifying glass to check if there are any omissions.

b. Determination of sedimentation bacteria

First, the measuring instruments, culture dishes, etc. must be strictly disinfected and sterilized, and cultured and observed for no less than 48 hours in a 37oC constant temperature incubator. They can only be used after being confirmed to be sterile. Second, a 90mm sedimentation plate is generally used, 20mL of culture medium is injected, placed at the measuring point, and the lid is opened for exposure for 30 minutes. The culture dish is covered and turned upside down, and then cultured in a 30~35oC constant temperature incubator for no less than 48 hours and the number of colonies is counted with the naked eye, and the number of colonies generated is recorded, and then checked with a 5~10x magnifying glass to see if there are any omissions.