Difference between revisions of "Biogas-Plant/C3/Construction-of-the-Dome/English"

Construction of the Dome

Welcome to this Spoken Tutorial on-

• Construction of the dome of the Digester tank.

• digging of the pit and
• laying the foundation.

• digging of the pit and
• laying the foundation

are available on Spoken-tutorial.org website.

Construction of the Dome

We will learn:

• The step-by-step procedure for constructing a dome.

• The step-by-step procedure for constructing a dome.

Slide 3 Construction of the Dome

What is a dome?

• an arch like structure
• placed on the Digester tank
• where the Biogas is collected.

[[Image:]]

• Steel rods
• Chicken mesh and
• Steel wire

Detailed specifications of these are mentioned-

• In the tutorial on materials required.

Now put 12 marks on the circumference of the circle

And number them from 1 to 12, as shown.

These 12 marks should be separated-

• by a distance of two feet from each other.

Hammer the 10-inch steel rods upto 2 inches in the ground.

Remember that they have to be removed later.

• We’ll make an outer circle around the hammered 10-inch steel rods.

Use an iron rod having hollow ends.

With this iron rod, bend the 12-ft steel rods to form a circular shape.

• Around the smaller 10-inch steel rods, as shown.

We will need two 12-ft rods to complete the circle.

• to the 10-inch steel rods using steel wires, as shown.

Ensure that the knot is tied very tightly and the steel rod circle is very stable.

This is the base of the dome.

Hence, it has to be very strong to bear the load of the plastered dome later.

• in the center of the circle, as shown.

Hammer the bamboo stick up to 2 inches in the ground.

Ensure that-

• it can stand firmly by itself and
• can be easily removed later

This bamboo stick should be able to-

• temporarily support the frame of the dome.

• and bend a 12-ft long steel rod to form an arch like shape.

This arch will give the semi-circular shape to the dome.

Hence, ensure that the arch is symmetric on either side when bent.

Similarly, bend 2 more 12-ft rods to form arches.

• Exactly how the arches have to be placed on the circumference using a diagram.

• Secure one end of the arch at rod number 1.
• And the other end of the arch at rod number 7.
• This will ensure perfect symmetry to the arch
• And it will rest on the bamboo stick in the centre.

• The arch together with the hammered 10-inch steel rod and the circular ring.

This pic shows only the circular ring and the 10-inch steel rod being tied. Replace with a picture of arched iron rod also.

Show arrow where the bent steel rod has been tied with hammered steel rod

Secure the second arch to rod number 3, and rod number 9.

And secure the third arch to rod number 5 and rod number11.

• at an angular separation of 60 degrees at the base

Next, carefully slide the steel rods at the top-

• Such that a small gap is left open in between.
• Tie the steel rods using the steel wires as shown.
• Intersection of the three arches will look like a triangle.
• The sides of the triangle should be approximately 2.5 inches.

As shown in the image-

• The top view of the framework should look like this after tying.

• the exact position of the open triangular gap using the bamboo stick

• This gap is where the main gas pipe of 1 inch diameter will fit.

• circular rings with the remaining 12-feet steel rods.

• circular base
• semi-circular arches

• they can be placed on the arches, as shown.

The rings have to be uniformly separated-

• by a distance of 8 inches between each of them.

1. The length of the steel rod would depend upon-
   • the position of the circular ring on the frame.
2. Longer steel rods would be required-
   • as we gradually go from top to bottom.

• the steel rods to the required length before we fix the rings.

For the first ring,

• which is the smallest ring at the top,
• we will need approximately-
  • 4 ft and 7 inch steel rod (adding 2 feet extra for tying).
• Diameter of this circular ring will be 10 inches

For the second ring,

• we will need approximately 7 ft 1 inch of steel rod
• Diameter of this ring will be 1 foot and 7 inches

For the third ring,

• 9 ft and 8 inches steel rod would be required
• Diameter would be 2 ft 5 inches

Fourth ring will require

• 12 ft 3 inches long steel rod.
• Diameter of this ring will be 3 ft and 3 inches

Fifth ring will need

• 14 ft 10 inches long steel rod
• Diameter of this ring will be 4 feet 1 inch

Sixth ring will require

• 17 feet 4 inches long rod.
• Diameter of this ring will be 4 feet and 10 inches

Remember-

• as mentioned while explaining the first circular ring

• an extra 2 feet has been calculated-

• for tying the rods together with steel wires for all the 8 rings.

• And the diameter for all the 8 rings is calculated excluding the 6 inches.

Both will be used for making the circular rings and also the entrance of the dome.

Measurements for these two are-

• Seventh ring will require 20 ft and 10 inches long steel rod.

• And for eighth ring 23 ft and 5 inches long steel rod would be required.

• Keep in mind that this includes the measurement for the bent rods as well

• An important thing to be done is-

• Length 4 ft in an inclined position inside the frame of the dome.

Note that-

• Bamboo sticks have to be spread out uniformly from the centre of the base.

1. And should be firmly rested against the circular rings or the arches.
2. These sticks will further give support to the frame of the dome.

Arrow at the scale fit between two circular rings

1. Then you will get a uniform distance of 8 inches between each circular ring.
2. To confirm this, use a 1 foot steel scale having two hooves.
3. The distance between these two hooves should be 8 inches.
4. And it should fit in between two circular rings as shown here.

However, you may ignore minor variations, if any.

• To fix vertical rods on the frame.

Between two half-arches -

• Fix a steel rod-
  • of length 5 ft and 5 inches, bisecting the two main arches.

• Tie this rod using-
  • steel wires from the base ring upto the first ring, as shown in the image.

• Similarly, fix two more steel rods
  • of 4 ft and 7 inches
  • bisecting the half-arch and the 5 ft and 5 inches steel rod.

Tie these two rods using steel wires from the base ring upto the second ring, as shown.

Please note-

1. Between the fifth and sixth 10-inch hammered steel rod, do the following:
   • The 4ft 7 inches long steel rod has to be bent and tied to the 6th ring.
2. This is done to make space for the entrance of the dome as shown in the image.

Note that, in both cases-

• Extra 3 inches have been left at the top.
• For the ease of tying the steel wire to the circular rings.

However it is to be noted that -

• between 6th and 8th ring will be the gap or the entrance to the dome.

Animation of the dome to show the gap prominently.

Size of this gap would be approximately-

• 2 ft of width and
• 2 ft of height

Bend the 7th rod-

• to make the upper side of the entrance, as shown in the image.
  

And bend the 8th ring downward.

This will make the lower end of the gap or entrance, as shown in the image.

Start covering the frame tightly with the mesh, from top to bottom.

[[Image:]]

Show arrow at the hook

• stretch the mesh tightly and tie it to the frame with steel wires.

This can be done by using a metal hook.

To tighten the layers of the chicken mesh-

1. Insert the hook into the hole(s) of the two layers
2. Rotate the hook by stretching the mesh
3. And simultaneously entwining the mesh(es).

• if the chicken mesh is not stretched tightly then-
• cracks might appear later while plastering the dome.

Show arrow on Chicken mesh at the nape of the frame

Reason for this will be explained while fixing the dome on the digester tank.

This would form approximately 3 layers over the dome.

• to hold the cement firmly while plastering the dome.

• is the mason getting inside the dome through the same gap or the entrance.

• remove the bamboo sticks placed inside for support.

Please note-

• that the sticks have to be gently removed so as to not disturb the frame of the dome.

1. Before shifting untie the 10 inch hammered steel rod from the base ring.

1. And make sure of re-tying the loose ends of the mesh.

• Constructing a dome for the Biogas plant.

Summary:

We have learnt:

The step-by-step procedure to construct the dome of the Digester tank.

In this tutorial we learnt:

Step-by-step procedure to construct the dome of the Digester tank.

Acknowledgements

This video was created by:

Spoken Tutorial Project with inputs from Rural-ICT team, IIT Bombay.

Spoken Tutorial Project with inputs from Rural-ICT team, IIT Bombay.

http://spoken-tutorial.org/NMEICT-Intro

http://ruralict.cse.iitb.ac.in/ in

http://spoken-tutorial.org/NMEICT-Intro

http://ruralict.cse.iitb.ac.in/ in

Pictures and technology support:

Courtesy:

Bhagirath Rural Development Foundation

Village- Zarap, Taluka- Kudal,

Dist.- Sindhudurg

Pictures and technology support:

Courtesy:

Bhagirath Rural Development Foundation

Village- Zarap, Taluka- Kudal,

Dist.- Sindhudurg

Thank you for joining.