Dionex As - Syringe Speed and Tubing Size Guidelines

3 • Operation and Maintenance
Doc. 065051-03 1/08 97
3.8 Syringe Speed and Tubing Size Guidelines
The AS is capable of delivering at a maximum pressure of 690 kPa (100 psi).
Several factors affect the system backpressure, including the syringe speed,
syringe size, and the IDs and lengths of the sample loop and the tubing used to
connect the inject port and the injection valve. Use the following formula to
determine the backpressure produced by these factors:
backpressure = cm of tubing x kPa (psi)/mL/min/cm (from Table 3-10
) x mL/min
(from Table 3-11
or Table 3-12)
Example: 30 cm of 0.254-mm ID tubing x 1.6 kPa/mL/min/cm x 2.40 mL/min
(5 mL syringe at speed 2) = 115 kPa
Tubing ID Backpressure in kPa (psi) per
mL/min per cm of tubing
Volume in μL per
cm of tubing
0.127 mm (0.005 in) 25 kPa (3.6 psi) 0.13
0.178 mm (0.007 in) 6.5 kPa (0.94 psi) 0.25
0.254 mm (0.010 in) 1.6 kPa (0.23 psi) 0.51
0.330 mm (0.013 in) 0.55 kPa (0.079 psi) 0.86
0.508 mm (0.020 in) 0.10 kPa (0.014 psi) 2.03
Table 3-10. Tubing Volume and Backpressure
Sample Syringe Size Sample Syringe Speed Flow Rate (mL/min)
100
a
, 250, 500, and 1,000 μL
a. The maximum flow rate for a 100 μL syringe is 0.60 mL/min.
10.06
20.12
30.24
40.60
51.20
5 and 10 mL
b
b. In general, if you are using a 5 or 10 mL syringe, select a syringe speed of 1 or 2.
11.80
22.40
34.80
47.20
5 15.00
Table 3-11. Flow Rates Provided by the Sample Syringe