Hydrodynamic calculation Howell-Jet valve

The Howell-Jet is a type of valve used for dam outlets. The valve uses a flow-shaped body which moves in the direction of the longitudinal axis inside the valve. The water jet leaving the valve has the shape of a hollow cylinder. Unlike the Howell-Bunger closure, the Howell-Jet has a more complex design that must provide control of the movement of the bypassed element outside the valve.

Hydrodynamic calculation Butterfly valve for pump operation (lattice disc)

Today it is required from the butterfly valve to be able to safely close the piping at maximum flow. When closing from an open position, the disc resists the current flowing. The flow is very complex in this case and in certain opening positions the valve is extensively stressed by hydrodynamic forces. The dynamic effects of the flow are

Hydrodynamic calculation Gate valve (through conduit)

The gate valve is a relatively old and proven type of valve that is most often used to close pipeline.

Hydrodynamic calculation Butterfly valve (double disc)

Today it is required from the butterfly valve to be able to safely close the piping at maximum flow. When closing from an open position, the disc resists the current flowing. The flow is very complex in this case and in certain opening positions the valve is extensively stressed by hydrodynamic forces. The dynamic effects of the flow are

Hydrodynamic calculation Butterfly valve (lattice disc)

Today it is required from the butterfly valve to be able to safely close the piping at maximum flow. When closing from an open position, the disc resists the current flowing. The flow is very complex in this case and in certain opening positions the valve is extensively stressed by hydrodynamic forces. The dynamic effects of the flow are

Multi-hole cage

The multi-hole cage is designed for flow control. It consists of a hollow cylinder, in the wall of which a system of holes is drilled. The size of the throttling cross-section is controlled by exposing the field of these holes with the upper edge of the seat. A single stream of medium is fragmented into many local streams.

The flow characteristic on the position of the drive

To determine the water shock or to determine the flow in the valve, we need to know the flow characteristic, which depends on the stroke of the drive.

Power screws

The power screws are used to convert the rotary motion into a sliding one (rarely the other way around). They are commonly used as guide screws for machine tools, screws for presses and jacks.

Multi-stage valve

The control valve, which must prevent cavitation, must be made for the given parameters and must be unique for the given situation (series-produced valves will not be functional for all situations). To prevent cavitation, it is necessary to use a multi-stage valve (there must be a gradual pressure drop in the valve by means of orifices),

Buckling

The analysis and design of compression members can differ significantly from that of members loaded in tension or in torsion. If you were to take a long rod or pole, such as a meterstick, and apply gradually increasing compressive forces at each end, very small axial deflections would happen at first, but then the stick would bend (buckle),

Contact stress (sphere)

The most general example of contact stress occurs when each of the contacting bodies has two different radii of curvature-the radius in the rolling plane is different from the radius in the plane perpendicular thereto, both planes passing through the axes of thrust forces.

Contact stress (cylinder)

When two bodies with curved surfaces are pressed together, the line of contact changes to the contact surface and the stresses in the bodies become spatial. Contact stress problems occur at the point of contact of the wheel with the rail, in the valve manifolds of internal combustion engines between cams and valve tappets, in gear engagement

Allowable Hertz pressure

It is the pressure that arises at the point of mutual force interaction of two bodies with defined surface curvature.

The bolt connects 2 flanges (torque load)

Serious bolt failures often occur in the operation of machines and machinery. In some cases, this phenomenon occurs even when the designer is convinced of sufficient safety of the bolted connection (given the external load conditions). The failure is most often caused by the underestimation of the limit state of the bolt connection or by

The cross pin connects 2 flanges (torque load)

In the marked diameter d1 and there must be no other weakening element in the cross-section in which the pin is located.

The advantage of this connection is easy assembly and disassembly. The disadvantage is the low manufacturing precision and consequent consequences for limited speeds and small torques.

Hydrodynamic calculation Needle valve - closing flow against the direction of movement of the piston

When designing a Needle valve, it is necessary to recognize several important parameters that express the hydraulic conditions and dynamic effects of flow in the valve. The basic parameters are the cavitation coefficient, the pressure loss, the flow rate and the resulting hydrodynamic forces acting on the movable part of the valve.

Hydrodynamic calculation Needle valve

When designing a Needle valve, it is necessary to recognize several important parameters that express the hydraulic conditions and dynamic effects of flow in the valve. The basic parameters are the cavitation coefficient, the aeration coefficient, the pressure loss, the flow rate and the resulting hydrodynamic forces acting on

Hydrodynamic calculation Howell-Bunger valve

The Howell Bunger valve today is one of the most widely used valves of dam outlets. Its construction is simple and the operating forces during opening are relatively small. Other advantages compared to other types of valves include efficient effluent damping as well as good aeration of water, which can often be critical to improving its quality.

Articulated trunnion in the rod

The trunnion is used to pivot the machine parts that transmit forces perpendicular to the trunnion axis. The trunnions can also be used for short axes such as wheels, pulleys, etc. They are usually mounted with clearance, allowing relative movement. The connecting Trunnions must be secured against axial displacement.

Key(s) for shaft-hub connection

If the shaft is loaded with the bending moment in the joint, the bending stress must be checked. If the shaft is loaded with a shear force in the joint, the shear stress must be checked. The shaft may be load in the joint by axial force. The shaft must be checked for axial stresses. When calculating the different load types,

Hydrodynamic calculation Butterfly valve (lenticular disc)

Today it is required from the butterfly valve to be able to safely close the piping at maximum flow. We need to know not only the mean values of the hydrodynamic forces and torque values, but also the pulsation, the maximum amplitude, when designing the butterfly valve and the connecting pipe. We also need to fully understand the effect

Hydrodynamic calculation Spherical valve

Today it is required from the spherical valve to be able to safely close the piping at maximum flow. When closing from an open position, the body resists the current flowing through not only the internal rotating body but also through the obstruction of the outside. The flow is very complex in this case and in certain opening positions the valve

Maximum allowable pressure PS of a valves

Maximum allowable pressure PS must be based on the most stringent conditions, which act on the valve. According to the maximum allowable pressure, the PN valve must be selected.

Cavitation for Outlet piping and valves

In practice, however, zero pressure in the pipeline cannot arise because water is excreted out of the water when the pressure drops, the gases contained in the water and forming water vapor. At normal temperatures, the water vapor pressure is about 0.1 m of the water column and therefore the cavitation boundary will be 10 m under the pressure.

Hydrotechnical calculation for Outlet piping

It is used to drain excess water from the dam, if necessary, to empty the dam. Each outlet has at least two valves: operational and revision. To achieve complete safety, an emergency valve is placed, which is permanently in the open position and is designed to quickly close the piping in the most critical cases.

The easiest and oldest way joints. It is a joint with a shape contact. The pin serves primarily to ensure the mutual positioning of the two parts. They are cylindrical or conical. The pins are dimensioned under simplified assumptions without will and without the pressing effect. When designing a pin, the cross section of the pin in the shear area

Longitudinal pin for shaft-hub connection

The easiest and oldest way joints. It is a joint with a shape contact. The pin serves primarily to ensure the mutual positioning of the two parts. They are cylindrical or conical. The pins are dimensioned under simplified assumptions without will and without the pressing effect. When calculating the pin, the length of the pin should not be considered,

Allowable stress

Reliable use of the products depends on how the designer ensures that the maximum stress in their critical locations is less than its limit value. This inequality must be met with sufficient margin to cover all sources of uncertainty of the relevant quantities; Under these circumstances, violation may occur only in exceptional circumstances.

The pipe line is firmly anchored at both ends - one ends is anchored in the foundations of the intake and the other in the foundations of the power house. Apart from these, anchorages are installed at bends and also near the expansion joints of long straight sections. Axial forces acting upon pipes are taken up by the anchors. The pipe is axially fixed

Effective closing time factor

The water hammer formula is valid assuming linear flow characteristics (at even closure - the linear relationship between the flow and the position of the closure valve). This assumption is difficult to accomplish with most valves without pre-treatment (modification of structural characteristics). Only a partial part of the total stroke influences

Calculation dimensions for drive by parallel or diagonal square head ISO 5211

The advantage of this connection is easy assembly and disassembly. The disadvantage is the low manufacturing precision and consequent consequences for limited speeds and small torques.

Calculation dimensions for drive by key(s) ISO 5211

The feather key are used to transfer the torque between the shaft and the hub. The feather key are inserted into shaft and hub grooves. The torque is transmitted only by the flanks of the feather key.

Bolt stressed by bending

The additional bend in the connecting screws must be avoided as the resulting bending stress can be several times greater than the tensile stresses of prestressing and operating forces.

The stress in pipe when changing temperatures

The piping system can be designed with expansion joints to prevent axial forces from changing the temperature, but the piping system may become uneconomic (expensive). Another disadvantage of the expansion joint is the non-transfer of the axial forces, so that if the expansion joint is inappropriately positioned in the duct system containing a member

Water hammer

Is a pressure surge or wave caused when a fluid, usually a liquid but sometimes also a gas, in motion is forced to stop or change direction suddenly, a momentum change. A water hammer commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe. This pressure wave can cause major