Safety risk downplayed in pipeline valve decision

WASHINGTON — Officials for a California company involved in a deadly
pipeline explosion last September acknowledged Tuesday

that four years
before the accident they rejected installing safety valves that could have
automatically shut off or remotely

controlled the flow of natural gas.
Pacific Gas and Electric Co. employees were questioned at a National
Transportation Safety

Board hearing about a 2006 memo that said
installing the valves would have “little or no effect on increasing
human safety or

protecting properties.”
Gas engineer Chih-hung Lee, author of the memo, said he considered
only industry studies, not

government studies, in reaching his
conclusions. Industry studies, he said, found that most of the damage in
natural gas

pipeline accidents occurs in the first 30 seconds.
However, when the pipeline ruptured on Sept. 9 under a suburban San
Francisco

subdivision, gas continued to feed a pillar of fire for an
hour and a half before workers could manually shut off the flow. Eight
people were killed, many more injured and dozens of homes destroyed.
Investigators pointed to a 1999 Transportation Department study

that
warned that there is a significant safety risk as long as gas was being
supplied to the rupture site and operators lacked

the ability to quickly
close manual valves.
“Any fire would have greater intensity and would have greater
potential for

damaging surrounding infrastructure if it is constantly
replenished with gas,” the government study said. “The degree of
disruption in heavily populated and commercial areas would be in direct
proportion to the duration of the fire.”
From the original1solenoidvalve
.

What Are The Basic Uses And Features of a Gate Valve

The valve which controls the flow of any type of
liquid flowing through pipes is termed as gate valve. It is used in most
of the buildings and homes where there are pipes. These valves include
round handles which are seen on the bulbous section of the

pipes.
Functions and Uses of Gate Valve
Gate
valve is one of the most popularly and widely used valves for

domestic
and industrial purposes. This valve is specifically used to obtain
uninterrupted flow of water. Used mostly in

isolated applications, this
valve is greatly preferred because once the valve is in an open
position; there is complete drop in

the pressure which is due to the
retraction of the gate into the bonnet.
According to specific
designs, this valve is

divided into different categories. The most
commonly used valves include the flexible wedge and the solid wedge gate
valve.

There are different types of flexible wedge valves which
utilises twin disc parts which are flexible. The parallel side valve is
one of the most commonly and widely used flexible wedge valve. These
valves are prominently used in stem systems as it can

withstand
expansion and contraction under varying climatic conditions
This
valve usually functions between open and closed functions. The pressure
in the pipes drops to a minimal level when the

valves are opened. These
valves are typically used as the initial valves in any plumbing
section. However, the valves cannot be

used to control the flow of water
in a linear style. It either operates to fully open or fully close the
flow.
A partially

open gate valve can cause vibrations

and
permanent damage to pipes. The seating part of the valves can also be
damaged by the fluid friction if the valves are

partially opened. In
these valves, the design is specifically aimed at completely blocking
the flow or completely allowing the

flow of water.
Gate Valve- The Different Types
The
rising stem and the non rising stem gate valve are the

two different
types of valves commonly used in most of the places today. The rising
stem valve is identified by a threaded

shaft which is rotated by a
handle fixed in the centre. The stem or the shaft rises when the handle
is rotated. It rises when

the valve is opened and descends when the
valve is closed. So it is easy to identify the position of the valve by
length of

shaft above.
The other variety of valve includes the
non rising stem valve which is used in places where there is space
constraint. It is mostly used in underground pipes. Rotating the handles
to the left opens the valves fully whereas rotating it to

the right
closes the valves completely. The stem of the valve does not rise while
opening and closing the valve.
Another

advantage of using these
valves includes the use of a single padlock to open and close the valve
whereas in the rising stem

valve, two padlocks are necessary. Gate valve
is available in different varieties in many of the leading online
stores.
From the original1solenoidvalve
.

Electric hard sealing butterfly valve

Electric hard sealing butterfly gold, chemical industry, building
materials, power stations, glass industries of the

ventilation,
environmental protection engineering cold or hot blast dongshen gas
pipeline, as gas medium flow adjustment or

cutting device.
Product features：
1, USES the midline type disc plate and steel welding new short
structure design and

fabrication of structure forms, compact structure,
light weight, convenient in installation, flow resistance small, big
circulation, avoid the influence of high inflation, convenient
operation.
2, inside without connecting rod, bolts, reliable

operation, long
service life. Can by multistage install, not the flow direction of
medium influence.
Application:
Electric hard sealing butterfly valve is a non airtight model
butterfly valve, widely used in building material, metallurgy,

mining,
power and other production process more than 300 ℃ temperature medium
nominal pressure on the pipeline for 0.1 Mpa,

used to connect or
adjusting for opening and closing dielectric quality.
Second, structure features:
This butterfly valve

is adopted with short line type disc plate steel
welding structure design and manufacture new structure forms, compact
structure, light weight, convenient in installation, flow resistance
small, big circulation, avoid the influence of high inflation,


convenient operation. Body without connecting rod, bolts, reliable
operation, long service life. Can by multistage install, not

the flow
direction of medium influence.
Three, working principle:
Driven by motor driving this butterfly valve actuator,

make the dish
plate in 90 ° scope free rotation to achieve on-off or regulatory medium
flow purpose.
At present, fluorine

-butterfly butterfly valve, lining rubber
butterfly valve, as a kind of used to attain a pipeline system hige and
flow control

components, already in petroleum, chemical, metallurgy,
water and electricity in many areas get very widely. In the butterfly
valve technology already male know, its sealing form used more sealing
structure, sealing materials for rubber, ptfe etc. Due to

restrictions
of structure characteristics, does not adapt the high temperature
resistant, high pressure and corrosion

resistance, abrasion resistance,
etc. Existing a more advanced butterfly valve is triple eccentric metal
hard seal butterfly valve, the valve body and seat

for conjoined twins
components, heat-resistant, seating surface layer surfacing corrosion
resistant alloy material. Multi-layer

soft fold type sealing ring fixed
in the valve plate, this butterfly valve and traditional butterfly
valve, compared with high

temperature resistant no friction, open the
operation of the light, closing with transmission’s torque increases to
compensate

for sealing, improve the butterfly valve sealing performance
advantages and prolong the service.
From the original1solenoidvalve
.

The advantages of ball valves

Ball valve and plug valves are belonging to the same type of valve, the

only difference is that ball’s shut down parts is sphere. The sphere rotates around the center line of valve to achieve the goal of

opening and closing. Ball valve is mainly used to cut，distribute and change the direction of media flow. Ball valve is a new type of valve

which is widely used in recent years. It has the following advantages:
1. Less fluid resistance. The resistance coefficient is equal

to the tabulation when they have the same length.
2. Simple structure, small size and light weight.
3. Close and reliable. Ball

valve‘s surface material is widely used in plastic industry and vacuum system.
4. Its Easy to operate, opening and closing rapidly.

It just as long as the rotation 90 °from fully open to fully closed. And it also provide more convenient for remote control.
5. It’s

easy to repair. Ball valve has a simple structure and its sealing ring is generally active. All of them also leave convenient for removal

replacement
6. In the fully open or fully closed, the body and the seat’s sealing surface of valve were isolated the medium. So, even

when the medium through, it will not cause erosion of the valve sealing surface.
7. Wide range of applications. Its diameter has a

wide range from small to a few millimeters to several meters. So it can even be widely used in high vacuum and high pressure.
 Now, ball valve has been widely used in petroleum, chemical, power generation, paper, nuclear,

aviation, rockets and other departments, as well as people’s daily lives.
From the original1solenoidvalve
.

Types of Solenoids and their Applications

Electromechanical Solenoid – Electromechanical
solenoids consist of an electromagnetically inductive coil, wound around
a movable steel or iron slug (termed the armature). Electromechanical
solenoids are used in electronic paintball markers, pinball machines,
dot matrix printers and fuel injectors.

Rotary Solenoid – Rotary solenoid is an
electromechanical device used to rotate a ratcheting mechanism when
power is applied. Rotary solenoids are used rotary snap-switch
automation in electromechanical controls.

Rotary Voice Coil Solenoid – This is a rotational
version of a solenoid. Typically the fixed magnet is on the outside, and
the coil part moves in an arc controlled by the current flow through
the coils. Rotary voice coils are widely employed in devices such as
hard disk drives and floppy/CD drives.

Pneumatic Solenoid Valve – Pneumatic solenoid valve
is a switch for routing air to any pneumatic device, usually an
actuator, allowing a relatively small signal to control a large device.
It is also the interface between electronic controllers and pneumatic
systems.

Hydraulic Solenoid Valve – Hydraulic solenoid
valves are in general similar to pneumatic solenoid valves except that
they control the flow of hydraulic fluid (oil). Hydraulic machinery uses
solenoids to control the flow of oil to actuators that deliver
mechanical energy. Solenoid-controlled valves are often used in
irrigation systems to open and close small pilot valve, which in turn
activates the main valve by applying fluid pressure. Solenoids are also
in everyday household items such as washing machines to control the flow
and amount of water into the drum.

Transmission solenoid – Transmission solenoids
control fluid flow through an automatic transmission and are typically
installed in the transmission valve body.

Automobile starter solenoid – The starter solenoid
receives a large electric current from the car battery and a small
electric current from the ignition switch. When the ignition switch is
turned on (i.e. when the key is turned to start the car), the small
electric current forces the starter solenoid to close a pair of heavy
contacts, thus relaying the large electric current to the starter motor.

From the original1solenoidvalve
.

About 3-way Solenoid Valve Operation

I took the brewhead 3-way solenoid valve off, and surprisingly I found
the spring around that solenoid nucleus is a lot softer than I would
expect. I know the pressure from brewing boiler could get about 12 bars
when water expands, so how could this spring hold that much pressure? It
is kind of stupid to ask, but I just really don't understand it. I also
noticed there is another harder spring that holds the viton seal of
solenoid nucleus, but it seems it has nothing to do with the functioning
of solenoid valve.
When the solenoid valve is active (during extraction), the coil

pushes the
piston to the closed position using electromagnetic force. This force
takes the place of the stiff spring you are referring to and resists the
extraction pressure. When de-energized, the magnetic force is removed
and the light spring returns the piston to the open position and lets
the water flow out. This is a "normally open" (NO) type solenoid. A
boiler fill type solenoid will work in reverse, opening when energized
(well you can use NO, but that would degrade its service life and the
programming for the controller is different, so dont just swap them).
From the original1solenoidvalve
.

new solenoid valve

I tested a new solenoid valve that RJ gave me. It is a two way control
solenoid valve, which means it has two solenoid one it. This new
solenoid valve reacts very fast, I love that sound when it was
working–powerful.
However, besides the fast reaction, this new solenoid valve is very the
same as the old one in the sense of control–as shown in the video, the
only way that controls the pneumatic rod maintaining in
a particular position is let it vibrates in a high frequency around that
position (name this method “vibration method”).
A big problem with this system is: uncertainty. With the same input
to the pneumatic cylinder, it results different rod positions! This
shown that the system is time varying. Thus, using “vibration method” is
definitely a bad idea.
Therefore, it is necessary to change the hardware:
B and B’ are solenoid control valves. When B apply air pressure and

B’
exhaust air, the rod moves forward; wen B’ apply air pressure and B
exhaust air, the rod moves backward; when both B and B’ apply air
pressure, the rod will stand still.
From the original1solenoidvalve
.