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close this book A training manual in conducting a workshop in the design, construction, operation, maintenance and repair of hydrams
close this folder Session 4: Measuring heads and distance (2-4 hours)
View the document Handout 4A: Calibrating a sight level
View the document Handout 4B: Using a sight level
View the document Handout 4C: Alternate ways of measuring heads
View the document Handout 4D: Alternate ways of measuring heads
View the document Handout 4E: Distance and head measurement worksheet

Session 4: Measuring heads and distance (2-4 hours)

Total Time: 2-4 hours

OBJECTIVE:

By the end of this session the trainees will have demonstrated skills in measuring heads by using sight levels, hose levels, pressure gauges, and in measuring distances using their stride and sight levels.

OVERVIEW:

At a potential hydram site trainees will perform a series of measurement procedures for determining the head of a stream/spring, using sight levels, hose levels and pressure gauges (where applicable). In addition trainees will measure the distance from the point where water will be taken from the stream/creek to where the ram will be installed using tape measures and their stride.

MATERIALS:

• Handouts 4A - 4E

 

• 15 ft of 1x2 lumber (or something similar which is straight) and string.

TOOLS:

• sight levels: 1 per pair of trainees; calibrated

 

• before session

 

• tape measures

 

• clear hose or tubing

 

• pressure gauges

*TRAINERS NOTES:

1. Distances and heads for trainee practice must be identified and measured ahead of time.

2. 3-4-5 triangle sight level should be pre-cut, since purpose of this activity is to measure not construct.

3. Pre-construction of site levels, weirs is recommended.

4. Time and available materials may make some techniques impractical. Select techniques ahead of time.

 

PROCEDURES

NOTES

1.

Distribute the handouts and go over the objective of the session.

 

2.

Describe the total activity and the techniques the trainees will be using .

 

3.

Divide the trainees into pairs making certain the total competency of each group is about the same.

 
 

Part I: Head Measurement

 

1.

Start by demonstrating how to calibrate sight level and then have the trainees calibrate their sight levels and measure the height of their eyes.

 

2.

Give the trainees the task of measuring the drive head and the delivery head of either an existing or a future hydram using a sight level.

 

3.

The trainees should next compare measurements and any measurements that seem out of line should be rechecked along with the sight level calibrations.

 

4.

The trainees should build sight level from indigenous materials using a 6 foot, 5 ft., and a 4 ft. 1 x 2, nails, string, and a rock. The three boards should be nailed together to form a right triangle. The string is attached to the 90 corner of the triangle with the rock attached to the other end (see handout 4C). With , the triangle held so the string remains parallel to the longer leg, one can sight down the shorter leg perfectly horizontally. These indigenous sight levels are now used to measure the same heads

It may be best to simply describe how this simple sight level works. If necessary to construct, trainer should pre cut lumber.

5.

Measure the same head using a clear

This is a very accurate technique, but cumbersome to practice plastic hose or tube filled with water with one end of the hose attached to a stick of known length (see Handout 4D).

6.

If there is a hydram installed at the site, attach a pressure gauge to the drive and delivery side and give the trainees the task of calculating the heads from the pressure readings. If this is a potential storage tank to the hydram site, then fill the pipe with water and ' attach a pressure gauge. Pressure readings should be taken and the delivery head calculated.

 

7.

If the sight levels are of the kind that have more than one horizontal cross hair, explain to the trainees how to use these levels for distance measuring .

 

8.

With the help of their partner, each trainee will measure ten normal paces using the tape measure and then divide by ten to determine their pace.

 

9.

Give the trainees the task of measuring a distance using their pace .

 

10.

Have them then measure a distance using a tape measure; compare the two measurements.

 

11.

The groups should then be given a task of measuring the drive and/or the delivery pipe distance.

 

12.

Back in the classroom, discuss any variations of the readings taken and the degree of accuracy that can be expected with each method used.