There are many structures of piston nitrogen making machine, which can be divided into single-stage, double-stage and multistage according to the shortened series. According to the setting method can be divided into mobile and robust two. According to the equipment of the cylinder, it can be divided into vertical, horizontal, viewpoint, symmetrical balance and opposition. According to the control method can be divided into unloading type and pressure switch type two. Among them, the unloading control method means that when the pressure in the gas tank reaches the set value, the nitrogen maker automatically stops working.

Cv is one of the important parameters for selecting the scheduling valve of the nitrogen maker. The definition of the fluency of the scheduling valve of the nitrogen maker is: When the scheduling valve of the nitrogen maker is fully open, the pressure difference between the two ends of the valve is 0.1MPa, and the fluid density is 1g/cm3, the flow number of the scheduling valve of the nitrogen maker per hour flow diameter is called fluent only adjustment, also known as the flow coefficient, which is marked with Cv, the unit is t/h, and the Cv value of the liquid is calculated according to the following formula. The nominal diameter DN of the scheduling valve of the nitrogen machine can be determined by looking up the Cv value of Liulicai.

The flow characteristics of the nitrogen machine dispatching valve (nitrogen machine accessories) are that the relative flow rate of the medium flowing through the nitrogen machine dispatching valve is connected with its opening under the condition that the pressure difference at both ends of the valve is stable. The flow characteristics of the scheduling valve of nitrogen generator have linear characteristics, equal percentage characteristics and parabolic characteristics. The significance of the three injection characteristics is as follows:

(1) Equal percentage characteristic (logarithm)

The relative journey and the relative flow of the equal percentage characteristics are not connected in a straight line, and the change of the flow caused by the change of the unit journey at each point of the journey is inversely proportional to the flow at this point, and the percentage of the flow change is flat. Therefore, its benefit is that the flow is small, the flow changes small, the flow is large, that is, in different degrees of opening, with the same scheduling accuracy.

(2) Linear characteristics (linear)

The relative journey of the linear characteristic is connected to the relative flow in a straight line. The traffic change caused by the change of the unit journey is constant. When the flow is large, the relative value of the flow changes little, and when the flow is small, the relative value of the flow changes greatly.

(3) Parabolic characteristics

The flow rate changes proportionally to the two sides of the journey, and has roughly linear and equal percentage characteristics.

From the analysis of the above three characteristics, it can be seen that in terms of its scheduling effect, the equal percentage characteristic is the best, its scheduling is unchanged, and the scheduling effect is good. The parabolic characteristics are better than the linear characteristics of the scheduling effect, can be based on the application of different occasions, screw nitrogen machine to select any of the flow characteristics.

The scheduling valve of the nitrogen generator is composed of two parts: the electric scheduling valve or the pneumatic scheduling valve. The dispatching system is divided into straight-through single-seat type and straight-through two-seat type. The latter has the characteristics of smooth adjustment, small operation and unchanged operation, so the straight-through world is suitable for occasions with large flow, high pressure drop and little leakage.