If translated literally from German, the gate is a shutter or shutter. The simplest design of such a device was still used by our distant ancestors. It can be found wherever there is stove heating even now - this is a retractable damper located in the stove chimney. Such a valve is used so that warm air does not escape from the heated room through the chimney .
If we go into a scientific language, the definition will be like this: a gate is a shut-off and regulating equipment with internal insulation for chimneys, ducts, industrial air purification systems and ventilation, capable of working at high temperatures. Its main element is a metal sheet moving along the guide corners or inside a slotted pocket. Depending on the application, the shutter is coated to protect it from the action of aggressive media.
Areas of use
A gate is a metal plate (or wedge), which, when the flow is blocked, can separate the mechanical inclusions passing through the damper. Due to this, similar closures are used on pipelines with different media: dry, bulk mixtures, heavy petroleum products, various gases and others.
Like most locking devices, gates can have a manual control system or an electric or hydraulic drive. This type of shutter in our time is most often used in chimney designs and in ventilation systems.
A significant quality of the gate is that in the open state it is completely removed from the pipe body, creating the least resistance to the residues of the outgoing gas. Thanks to this, gates are actively used in obtaining high vacuum.
Types of gates
There are two types of dampers: rotary and horizontal gates. The first is also called a throttle. This is a gate of the classical type, which is a plate that is mounted on a rotating axis. The axis is inside the chimney or pipe. The rotary gate is less reliable, therefore it is used only if it is not possible to install horizontal horizontally.
The horizontal sliding gate allows you to adjust the process by changing the cross-sectional area of the chimney channel due to the horizontal extension of the plate. Most often used in steel and brick chimneys. It is more reliable, and therefore, if there is a technical possibility, install a retractable gate. The plate of such a damper itself is perforated or has a cut. This is necessary so that the gate does not completely block the channel - these are the fire safety requirements.
Gate functions
Its functions vary depending on the application. If the gate is used in the pipeline system as shutoff valves, then it will perform the function of restricting the movement of liquid (bulk mixtures). Such a gate is also called cross over.
In the ventilation system, the gate acts as a device that regulates air flow. You can move the valve forward and backward, thereby changing the flow rate of air passing through the structure, blocking partially or completely the flow. Such a gate is called regulatory.
In the chimney, the gate is used as a regulator damper, which allows to partially or completely block the cross section of the smoke channel, which allows to reduce heat loss inside the room after the furnace.
The gate for the chimney performs another function - the draft regulator, that is, it acts as a control damper along the smoke. Here the principle applies: the more the cross section of the chimney channel is blocked, the less air enters, and the draft decreases. Conversely, the more the gate is open, the more air and draft is stronger, the combustion process is much more intense and faster.
Design specifics
The gate design is influenced by many factors: temperature of the transported medium, pipe cross-sectional shape, passage conditions, etc. The basis of the design is a metal sheet of different thickness, moving in a slotted pocket or along the guide corners.
The gates differ for various reasons. Allocate locking and butterfly valves, restricting the flow. According to the principle of operation, the gates are classified according to the type of drive: manual, pneumatic, hydraulic, electric, etc., and according to the type of construction, they distinguish between straight and oblique.
The direct gate is in appearance a classic damper. It is used in a forced-air ventilation system. Slanting gate is used in systems of industrial aspiration and pneumotransport. It is called “oblique” because of its installation at 45 degrees, and not as usual - perpendicularly, which allows very accurate and smooth metering of the air flow.
A very important point is what material the gate is made of. Depending on where the device will be used, it can be made of stainless, chrome or alloy steel.
Features of installation in the chimney
In a chimney, the gate is usually installed in two ways. First, the device is connected to the other elements of the chimney without additional fasteners. This method is called “pipe to pipe”.
In the second embodiment, the gate is located directly in the furnace or in the outlet pipe as a separate element, that is, the damper is integrated directly into the structure. With this design, the gate is installed at a height of not more than one meter, that is, close enough to the heater itself. This provides ease of valve control.
Installation in a ventilation system
Ventilation gates are usually installed at the fan outlet. This is the most common installation site. If the damper and fan are installed together, this design is called the starting gate. The valve here serves as a protective plug that prevents the engine from overheating when the fan starts. It is only necessary to start the fan operation when the gate is closed, since in the open state a large load is applied to the electric motor, which can lead to system breakdown.
When installing the gate, you must take into account the disadvantages of this device. For example, if the chimney is straight, then the presence of a valve will complicate the cleaning of the furnace from soot. And if the gate in the ventilation system does not have an automatic opening function, it is advisable to equip the fan with a frequency converter or soft starter.