Build N Tech Maintenance & Engineering

28/04/2021

25/09/2018

MAINTAINING THE PROPERTY (Build N Tech)

All maintenance work performed at Housing Authority properties can be categorized by the source of the work. Each piece of work originates from a particular source -- an emergency, the routine maintenance schedule, the preventive maintenance schedule, a unit inspection, a unit turnover, or a resident request.

22/09/2018

We are Introducing a New Maintenance Policy All Over Kerala

Required Trainees for this field

08/09/2018

Hydraulic Controls

08/09/2018

Hydraulic Flow Control
valves
Flow Control Circuits
Flow-Control Valves
Flow-control valves include simple or***ces to sophisticated closed-loop electro-hydraulic valves that automatically adjust to variations in pressure and temperature.
Figure 10-1. Fixed or***ce.
To control the speed of an actuator, most designers use flow controls. Air circuits normally need controlled flow because the plant air compressor is greatly oversized for almost any given circuit. Hydraulic circuits usually have a dedicated power source sized to meet the cycle time so flow restrictors are unnecessary.
Figure -2. Pressure- and temperature-compensated fixed or***ce.
Flow controls always generate some heat in hydraulic circuits, so consider some other method of controlling actuator speed where possible. The circuit examples in this chapter explain the types of flow-control systems and how to apply them.
Figure 3. Needle valve.
Figures 10-1 and 10-2 show symbols for fixed or***ces, rudimentary components that will control flow. A fixed or***ce can be a simple restriction in a line or a factory-preset control with pressure compensation and a bypass. Their low cost and the fact that they are tamper-proof are two main reasons for using fixed or***ces.
Figure 5. Flow control with bypass (or throttle valve).
Figure 10-1. Fixed or***ce.
To control the speed of an actuator, most designers use flow controls. Air circuits normally need controlled flow because the plant air compressor is greatly oversized for almost any given circuit. Hydraulic circuits usually have a dedicated power source sized to meet the cycle time so flow restrictors are unnecessary.
Figure 10-2. Pressure- and temperature-compensated fixed or***ce.
Flow controls always generate some heat in hydraulic circuits, so consider some other method of controlling actuator speed where possible. The circuit examples in this chapter explain the types of flow-control systems and how to apply them.
Figure 10-3. Needle valve.
Figures 10-1 and 10-2 show symbols for fixed or***ces, rudimentary components that will control flow. A fixed or***ce can be a simple restriction in a line or a factory-preset control with pressure compensation and a bypass. Their low cost and the fact that they are tamper-proof are two main reasons for using fixed or***ces.
Figure 10-4. Pressure- and temperature-compensated needle valve.
Use the needle valve shown in Figure 10-3 when control of fluid flow in both directions is necessary. Add the check valve arrangement shown in Figure 10-4 when a needle valve needs pressure compensation in both directions. These check valves, sometime referred to as bridge rectifiers, force fluid to flow through the needle valve in the same direction regardless of actuator movement. (Remember, pressure compensation only works in one direction of flow.)
Figure 10-5. Flow control with bypass (or throttle valve).
When talking about flow-control hardware, some manufacturers use different terminology. Normally the term flow control refers to an adjustable needle valve with an integral bypass, as pictured in Figure 10-5. This type of flow control meters flow in one direction and allows free flow in the opposite direction. However, some companies identify the flow control in Figure 10-5 as a throttle valve. These companies say a flow control must have a bypass and be pressure-compensated as shown in Figure 10-6.
Figure 10-6. Pressure- and temperature-compensated flow control.
When a hydraulic actuator needs accurate speed control, use a pressure-compensated flow control. System pressure fluctuations or load changes will cause actuator velocity to change. Regardless of the cause of the pressure differences, flow across the or***ce will change unless the flow control is pressure compensated. Only use a pressure-compensated valve when very accurate speed control is needed because its cost is as much as six times that of a non-compensated valve.

Types of flow-control circuits
Figure 10-7. Meter-in flow-control circuit – at rest.
There are three types of flow control circuits from which to choose. They are: meter-in, meter-out, and bleed-off (or bypass). Air and hydraulic systems use meter-in and meter-out circuits, while only hydraulic circuits use bleed-off types. Each control has certain advantages in particular situations.
Figure 10-7 shows a meter-in flow-control circuit for a cylinder. Notice that a bypass check valve forces fluid through an adjustable or***ce just before it enters the actuator. Figure 10-8 shows an extending hydraulic cylinder and indicates the pressures and flows in various parts of the circuit. With a meter-in circuit, fluid enters the actuator at a controlled rate. If the actuator has a resistive load, movement will be smooth and steady with a hydraulic circuit. This is because oil is almost non-compressible.
Figure 10-1. Fixed or***ce.

(to be continue next )

Build N Tech. Engineering
( Maintenance & Home service)
MAINTENANCE POLICY
The Property Management Department of Build N Tech is responsible for managing

04/09/2018

04/09/2018

ELECTRICAL INSTALLATION AND MAINTENANCE SKILL
NEEDS OF TECHNICAL COLLEGE GRADUATES FOR JOB CREATION AND SELF-RELIANCE IN KERALA STATE

What is meant by electrical installation?

An electrical installation is a combination of electrical equipment installed from a common electrical supply to fulfill a particular purpose. ... An electrical installation is a combination of electrical equipment installed from a common electrical supply to fulfill a particular purpose.

Build N Tech. Engineering
( Maintenance & Home service)
MAINTENANCE POLICY
The Property Management Department of Build N Tech is responsible for managing