Please note the following guide should be used only for selecting Checkfluid Products.
For Quick Search: Please Enter The Measurement Taken with Calipers
Want to know how to measure your port thread to see what size sampling valve you need? Watch our video below:
Jump to: Step 1 (Thread Measurement) > Step 2 (Sealing Forms) > Step 3 (Dash Sizes)
Step 1: Thread Identification
Use calipers to measure the diameter & thread pitch.
- For male threads measure the outside diameter
- For female threads measure the inside diameter
Match your measurements with the chart below; and continue to Step 2 for sealing forms
|
Outside Dia. Male
(mm)
|
Outside Dia. Male
(inches)
|
Inside Dia Female
(mm)
|
Inside Dia. Female
(Inches)
|
Pitch/Inch
TPI
|
Forms
|
Metric DIN/ Metric ISO 6149
|
BSPP (G) /BSPT (R)
|
NPTF
|
ORB/JIC/ORFS (UNF)
|
|
3.8 - 3.9
|
0.150 - 0.154
|
3.2 - 3.4
|
0.126 - 0.134
|
0.7
|
-
|
M 4
|
-
|
-
|
-
|
|
4.0 - 4.2
|
0.158 - 0.165
|
3.4 - 3.6
|
0.134 - 0.142
|
36
|
E, F, G
|
-
|
-
|
-
|
No. 8
|
|
4.6 - 4.8
|
0.181 - 0.189
|
4.0 - 4.2
|
0.157 - 0.165
|
32
|
E, F, G
|
-
|
-
|
-
|
No. 10
|
|
4.8 - 4.9
|
0.189 - 0.193
|
4.1 - 4.3
|
0.161 - 0.169
|
0.8
|
-
|
M 5
|
-
|
-
|
-
|
|
5.7 - 5.9
|
0.224 - 0.232
|
4.9 - 5.2
|
0.193 - 0.205
|
1
|
B
|
M 6
|
-
|
-
|
-
|
|
7.7 - 7.9
|
0.303 - 0.311
|
6.9 - 7.2
|
0.272 - 0.283
|
1
|
B, C, E,
|
M 8
|
-
|
-
|
-
|
|
7.7 - 7.9
|
0.303 - 0.311
|
6.6 - 6.9
|
0.260 - 0.272
|
1.25
|
B
|
M 8
|
-
|
-
|
-
|
|
7.7 - 7.9
|
0.303 - 0.311
|
6.8 - 7.1
|
0.268 - 0.280
|
24
|
E, F
|
-
|
-
|
-
|
5/16
|
|
7.0 - 7.9
|
0.275 - 0.311
|
6 - 6.9
|
0.236 - 0.271
|
27
|
D
|
-
|
-
|
1/16
|
-
|
|
9.5 - 9.7
|
0.374 - 0.397
|
8.5 - 8.8
|
0.335 - 0.346
|
28
|
B, C, D
|
-
|
1/8
|
-
|
-
|
|
9.5 - 9.7
|
0.374 - 0.382
|
8.5 - 8.7
|
0.335 - 0.343
|
24
|
E, F
|
-
|
-
|
-
|
3/8
|
|
9.7 - 9.9
|
0.382 - 0.390
|
8.9 - 9.2
|
0.350 - 0.362
|
1
|
A, B, C, E
|
M 10
|
-
|
-
|
-
|
|
9.7 - 9.9
|
0.382 - 0.390
|
8.6 - 8.9
|
0.339 - 0.350
|
1.25
|
-
|
M 10
|
-
|
-
|
-
|
|
9.7 - 9.9
|
0.382 - 0.390
|
8.4 - 8.7
|
0.331 - 0.343
|
1.5
|
-
|
M 10
|
-
|
-
|
-
|
|
9.4 - 10.3
|
0.370 - 0.406
|
8.3 - 9.2
|
0.327 - 0.362
|
27
|
D
|
-
|
-
|
1/8
|
-
|
|
10.9 - 11.1
|
0.429 - 0.437
|
9.7 - 10.0
|
0.382 - 0.394
|
20
|
E, F
|
-
|
-
|
-
|
7/16
|
|
11.7 - 11.9
|
0.461 - 0.469
|
10.6 - 10.9
|
0.417 - 0.429
|
1.25
|
-
|
M 12
|
-
|
-
|
-
|
|
11.7 - 11.9
|
0.461 - 0.469
|
10.4 - 10.7
|
0.409 - 0.421
|
1.5
|
B,C
|
M 12
|
-
|
-
|
-
|
|
11.6 - 11.9
|
0.457 - 0.469
|
10.1 - 10.4
|
0.398 - 0.409
|
1.75
|
-
|
M 12
|
-
|
-
|
-
|
|
12.2 - 12.4
|
0.480 - 0.488
|
11.2 - 11.4
|
0.441 - 0.449
|
1.5
|
-
|
M 12.65
|
-
|
-
|
-
|
|
12.5 -12.7
|
0.492 - 0.500
|
11.3 - 11.7
|
0.445 - 0.461
|
20
|
E, F
|
-
|
-
|
-
|
1/2
|
|
12.9 - 13.2
|
0.508 - 0.520
|
11.4 - 11.9
|
0.449 - 0.469
|
19
|
B, C, D
|
-
|
1/4
|
-
|
-
|
|
12.6 - 13.7
|
0.496 - 0.539
|
10.7 - 11.5
|
0.421 - 0.452
|
18
|
D
|
-
|
-
|
1/4
|
-
|
|
13.8 - 14.0
|
0.543 - 0.551
|
12.4 - 12.6
|
0.488 - 0.496
|
1.5
|
B, C, E
|
M 14
|
-
|
-
|
-
|
|
14.0 - 14.2
|
0.552 - 0.561
|
12.8 - 13.1
|
0.502 - 0.515
|
18
|
E, F, G
|
-
|
-
|
-
|
9/16
|
|
14.1 - 14.2
|
0.554 - 0.561
|
13.1 - 13.4
|
0.517-0.527
|
24
|
-
|
-
|
-
|
-
|
9/16
|
|
15.7 - 15.9
|
0.618 - 0.626
|
14.4 - 14.7
|
0.567 - 0.579
|
1.5
|
B, C, E
|
M 16
|
-
|
-
|
-
|
|
15.6 - 15.9
|
0.614 - 0.626
|
13.8 - 14.2
|
0.543 - 0.560
|
2
|
-
|
M 16
|
-
|
-
|
-
|
|
15.7 - 15.9
|
0.618 - 0.626
|
14.4 - 14.7
|
0.567 - 0.579
|
16
|
-
|
-
|
-
|
-
|
5/8
|
|
15.9 - 16.1
|
0.626 - 0.634
|
14.4 - 14.6
|
0.567 - 0.575
|
18
|
-
|
-
|
-
|
-
|
5/8
|
|
16.4 - 16.7
|
0.646 - 0.657
|
14.9 - 15.4
|
0.587 - 0.606
|
19
|
B, C, D
|
-
|
3/8
|
-
|
-
|
|
16.0 - 17.1
|
0.629 - 0.673
|
14.2 - 14.8
|
0.559 - 0.582
|
18
|
D
|
-
|
-
|
3/8
|
-
|
|
17.2 - 17.4
|
0.677 - 0.685
|
15.7 - 15.9
|
0.618 - 0.626
|
16
|
G
|
-
|
-
|
-
|
11/16
|
|
17.8 - 18.0
|
0.701 - 0.709
|
16.4 - 16.6
|
0.646 - 0.654
|
1.5
|
B, C, E
|
M 18
|
-
|
-
|
-
|
|
18.8 - 19.0
|
0.739 - 0.748
|
17.3 - 17.7
|
0.682 - 0.696
|
16
|
E, F
|
-
|
-
|
-
|
3/4
|
|
19.7 - 19.9
|
0.776 - 0.783
|
18.9 - 19.2
|
0.744 - 0.756
|
1
|
A
|
M 20
|
-
|
-
|
-
|
|
19.7 - 19.9
|
0.776 - 0.783
|
18.4 - 18.7
|
0.724 - 0.736
|
1.5
|
A
|
M 20
|
-
|
-
|
-
|
|
19.6 - 19.9
|
0.772 - 0.783
|
17.3 - 17.7
|
0.681 - 0.697
|
2.5
|
A
|
M 20
|
-
|
-
|
-
|
|
20.4 - 20.6
|
0.802 - 0.811
|
18.9 - 19.3
|
0.745 - 0.759
|
16
|
G
|
-
|
-
|
-
|
13/16
|
|
20.7 - 20.9
|
0.815 - 0.823
|
18.6 - 19.2
|
0.732 - 0.756
|
14
|
B, C, D
|
-
|
1/2
|
-
|
-
|
|
20.4 - 21.3
|
0.803 0.839
|
17.4 - 18.5
|
0.728 - 0.685
|
14
|
D
|
-
|
-
|
1/2
|
-
|
|
21.7 - 21.9
|
0.854 - 0.862
|
20.4 - 20.7
|
0.803 - 0.815
|
1.5
|
A
|
M 22
|
-
|
-
|
-
|
|
21.9 - 22.6
|
0.862 - 0.890
|
20.3 - 20.8
|
0.799 - 0.819
|
14
|
E, F
|
-
|
-
|
-
|
7/8
|
|
23.7 - 23.9
|
0.933 - 0.941
|
22.4 - 22.7
|
0.882 - 0.894
|
1.5
|
A
|
M 24
|
-
|
-
|
-
|
|
23.6 - 23.9
|
0.929 - 0.941
|
20.8 - 21.3
|
0.819 - 0.839
|
3
|
A
|
M 24
|
-
|
-
|
-
|
|
25.1 - 25.4
|
0.989 - 1.000
|
23.1 - 23.6
|
0.909 - 0.929
|
14
|
G
|
-
|
-
|
-
|
1
|
|
25.7 - 26.0
|
1.012 - 1.024
|
24.4 - 24.6
|
0.961 - 0.969
|
1.5
|
A
|
M 26
|
-
|
-
|
-
|
|
26.2 - 26.4
|
1.031 - 1.039
|
24.1 - 24.7
|
0.949 - 0.972
|
14
|
B, C, D
|
-
|
3/4
|
-
|
-
|
|
26.6 - 26.9
|
1.047 - 1.059
|
24.8 - 25.2
|
0.976 - 0.992
|
2
|
A
|
M 27
|
-
|
-
|
-
|
|
26.8 - 27.0
|
1.055 - 1.063
|
24.7 - 24.9
|
0.972 - 0.980
|
12
|
E, F
|
-
|
-
|
-
|
1 1/16
|
|
25.5 - 26.7
|
1.00 - 1.051
|
22.5 - 23.6
|
0.886 - 0.929
|
14
|
D
|
-
|
-
|
3/4
|
-
|
|
28.3 - 28.6
|
1.114 - 1.126
|
26.3 - 26.8
|
1.035 - 1.055
|
12
|
-
|
-
|
-
|
-
|
1 1/8
|
|
29.7 - 29.9
|
1.169 - 1.18
|
28.4 - 28.7
|
1.118 - 1.130
|
1.5
|
-
|
M 30
|
-
|
-
|
-
|
|
29.7 - 29.9
|
1.169 - 1.18
|
28.4 - 28.7
|
1.118 - 1.130
|
2
|
B, C, E
|
M 30
|
-
|
-
|
-
|
|
30.0 - 30.2
|
1.181 - 1.189
|
27.9 - 28.1
|
1.098 - 1.106
|
12
|
E, F, G
|
-
|
-
|
-
|
1 3/16
|
|
32.9 - 33.2
|
1.295 - 1.307
|
30.3 - 30.9
|
1.193 - 1.217
|
11
|
B, C, D
|
-
|
1
|
-
|
-
|
|
32.7 - 33.0
|
1.287 - 1.299
|
30.8 - 31.2
|
1.213 - 1.228
|
2
|
B, C, E
|
M 33
|
-
|
-
|
-
|
| 32.7 -33.8 |
1.289 - 1.330 |
32.4 - 33.4 |
1.275 - 1.315 |
11 1/2 |
D |
- |
- |
1 |
- |
|
32.4 - 33.2
|
1.276 - 1.307
|
31.1 - 31.3
|
1.224 - 1.232
|
12
|
E, F
|
-
|
-
|
-
|
1 5/16
|
|
35.7 - 35.9
|
1.406 - 1.413
|
34.4 - 34.7
|
1.354 - 1.366
|
1.5
|
-
|
M 36
|
-
|
-
|
-
|
|
35.6 - 35.9
|
1.402 - 1.413
|
33.8 - 34.2
|
1.331 - 1.346
|
2
|
B, C
|
M 36
|
-
|
-
|
-
|
|
36.2 - 36.5
|
1.425 - 1.437
|
34.2 - 34.4
|
1.346 - 1.354
|
12
|
G
|
-
|
-
|
-
|
1 7/16
|
|
37.7 - 37.9
|
1.484 - 1.492
|
36.4 - 36.7
|
1.433 - 1.445
|
1.5
|
-
|
M 38
|
-
|
-
|
-
|
|
37.8 - 38.1
|
1.488 - 1.500
|
35.8 - 36.4
|
1.409 - 1.433
|
12
|
-
|
-
|
-
|
-
|
1 1/2
|
|
41.1 - 41.3
|
1.618 - 1.626
|
39.1 - 39.3
|
1.539 - 1.547
|
12
|
E, F
|
-
|
-
|
-
|
1 5/8
|
|
41.6 - 41.9
|
1.638 - 1.650
|
38.9 - 39.6
|
1.531 - 1.559
|
11
|
B, C, D
|
-
|
1 1/4
|
-
|
-
|
|
41.7 - 41.9
|
1.642 - 1.650
|
40.4 - 40.7
|
1.591 - 1.602
|
1.5
|
-
|
M 42
|
-
|
-
|
-
|
|
41.6 - 41.9
|
1.638 - 1.650
|
39.8 - 40.2
|
1.567 - 1.583
|
2
|
B, C, E
|
M 42
|
-
|
-
|
-
|
| 41.5 - 42.5 |
1.633 - 1.675 |
41.1 - 42.1 |
1.619 - 1.660 |
11 1/2 |
D |
- |
- |
1 1/4 |
- |
|
42.6 - 42.8
|
1.677 - 1.685
|
40.6 - 40.8
|
1.598 - 1.606
|
12
|
G
|
-
|
-
|
-
|
1 11/16
|
|
44.7 - 44.9
|
1.760 - 1.768
|
43.4 - 43.7
|
1.709 - 1.720
|
1.5
|
-
|
M 45
|
-
|
-
|
-
|
|
44.7 - 44.9
|
1.760 - 1.768
|
43.4 - 43.7
|
1.709 - 1.720
|
2
|
B, C
|
M 45
|
-
|
-
|
-
|
|
47.4 - 47.8
|
1.866 - 1.882
|
44.8 - 45.5
|
1.764 - 1.791
|
11
|
B, C, D
|
-
|
1 1/2
|
-
|
-
|
|
47.4 - 47.6
|
1.866 - 1.874
|
45.3 - 45.5
|
1.783 - 1.791
|
12
|
E, F
|
-
|
-
|
-
|
1 7/8
|
| 47.5 - 48.6 |
1.872 - 1.915 |
47.2 - 48.3 |
1.856 - 1.9 |
11 1/2 |
D |
- |
- |
1 1 /2 |
- |
|
47.6 - 47.9
|
1.874 - 1.886
|
45.8 - 46.2
|
1.803 - 1.819
|
2
|
B, C, E
|
M 48
|
-
|
-
|
-
|
|
50.5 - 50.7
|
1.988 - 1.996
|
48.5 - 48.7
|
1.909 - 1.917
|
12
|
G
|
-
|
-
|
-
|
2
|
|
51.8 - 52.0
|
2.039 - 2.047
|
49.8 - 50.0
|
1.961 - 1.969
|
2
|
-
|
M 52
|
-
|
-
|
-
|
|
51.7 - 52.0
|
2.035 - 2.047
|
50.4 - 50.6
|
2.003 - 2.011
|
1.5
|
-
|
M 52
|
-
|
-
|
-
|
|
59.3 - 59.6
|
2.335 - 2.346
|
56.7 - 57.3
|
2.232 - 2.256
|
11
|
B, C, D
|
-
|
-
|
2
|
-
|
| 59.6 - 60.7 |
2.345 - 2.390 |
59.3 - 60.3 |
2.333 - 2.375 |
11 1/2 |
D |
- |
- |
2
|
- |
|
59.7 - 59.9
|
2.350 - 2.358
|
58.4 - 58.7
|
2.299 - 2.311
|
1.5
|
-
|
M 60
|
-
|
-
|
-
|
|
59.7 - 59.9
|
2.350 - 2.358
|
58.4 - 58.7
|
2.299 - 2.311
|
2
|
B, C
|
M 60
|
-
|
-
|
-
|
|
71.9 - 73.6
|
2.829 - 2.896
|
71.4- 73.0
|
2.810 - 2.875
|
8
|
D
|
-
|
-
|
2 1/2
|
-
|
|
79.7 - 79.9
|
3.138 - 3.146
|
78.4 - 78.7
|
3.087 - 3.098
|
1.5
|
-
|
M 80
|
-
|
-
|
-
|
Continue onto Step 2: Sealing Forms
