Ramkala Manufatureres

Dhayari Phata, Pune, Maharashtra

Open Pan Evaporimeter is used to calculate the evaporation loss of water in the atmosphere. It consists of Copper / Galvanize Pan, Wire Mesh, Fixed Point gauge, Measuring Cylinder, Thermometer & Wooden Platform. The Pan Evaporimeter consists of a cylindrical reservoir of Fixed diameter & depth is filled with water to a few centimeters below the rim. A fixed point gauge in a stilling well serves to indicate the level of water in the pan. A calibrated measuring cylinder is used to add or remove water at each observation to bring the water level to the fixed point. The cross - sectional area of the measuring cylinder is such that the number of millimeters of water added from the measuring cylinder divided by 100 gives the amount of water in millimeters which has evaporated from the pan during a given interval of time. The reservoir is covered with wire-mesh netting to protect the pan from birds & animals. A thermometer records the temperature of the water in the pan

Material

• The Pan Evaporimeter : The Pan Evaporimeter is made from Copper / Galvanize sheet (G.I.). The Dimension of pan should be 1220 mm + 3mm. The base of Pan is made from single piece of copper/ G.I. Sheet. The outer surface of pan is painted with three coats of chlorinated rubber paint and the inner surface tinned or painted uniformly.
• The Fixed Point Gauge : The Fixed - point gauge is made from brass rod of 10mm diameter. The stilling well is made from brass tube of 102 mm outside dia with a wall thickness of 3.0 + 0.5 mm & the base of made from cast brass.
• The Measuring Cylinder : The Measuring Cylinder is made from clear cast seamless acrylic plastic tubing & the bottom plate of clear acrylic Plastic Sheet. The dimension of the measuring cylinder made from acrylic plastic should be 122+ 0.3mm
• Wire Mesh : The Cover shall consists of a circular M.S. bar frame with cross pieces of bar. This frame is covered with G.I. wire netting. The Cover should properly fit on the outer rim of the pan.
• Thermometer : Thermometer of glass in liquid filled type with range 0 to 50^oc is supplied with pan
• Wooden Platform : Well seasoned wood/deodhar wooden planks are used for making platform. The size of platform should be 1225 x 1225 x 100 mm. The frame of platform is made from 11 nos. of wooden planks.

Specifications :

• Material
  
  • Pan evaporimeter - Copper sheet of thickness 1.0 0.1 mm.
  • Fixed point gauge and still well - Brass
  • Measuring cylinder - Clean cast seamless acrylic plastic tubing or brass sheet
  • Bottom plate - Acrylic plastic sheet
  • Thermometer clamp - Brass
  • Platform - Rot resistant lumber treated with creosote or other effective wood preservative

Dimensions : The dimensions of the pan evaporimeter shall be as given in figs. 8.1, 8.2, 8.3 and 8.4

The Cup Counter Anemometer is used for measuring the wind speed. The instrument has a cup wheel comprising of three conical cups with bedded edges and free to rotate in a horizontal plane. The cup wheel spindle is connected by worm gearing to a revolution counter mounted inside a water proof housing. The gear ratio between the cup and counter spindles is so chosen that the run of the wind is shown directly in kilometers and tenths. The counter mechanism has five figures and reads upto 9999.9 km. before repeating itself

Material :

• Cup - Copper Sheet/ Aluminium 0.71 Mm Thick
• Cup Arm & Socket - Aluminium Alloy
• Body & Lid - Cast Aluminium/ Brass
• Centre Spindle - Stainless Steel Rod
• Worm - Manganese Bronze Alloy
• Worm Wheel - Hard Brass
• Other Parts - Made from Non Rusting Material

Cup Rotar Assembly : Each of the three rotor cups shall have an internal Dia. of exactly 127.0 mm and be semi conical in shape. The spindle is supported on two bearings, ball bearing at top & thrust bearing at bottom. The assembly is made as per the instruction laid in IS - 5912

Worm & Worm Wheel : The worm wheel shall engage true with the threads on the worm without friction. The worm wheel shall be secured to the shaft of the counter by means of a steel pin. The gearing ratio shall be such that 32 revolutions of cup rotor produce one revolution of the worm wheel.

Body & Lid : The body and the lid are made from Aluminium casting and glass window only viewing the five figure wheels of counter. Each anemometer will be supplied with 18" long M.S. bar for fixing in concrete.

Counter : It is a non-reset, direct drive revolution counter adding one counter for each one tenth revolution. The figures of the counter shall be 7mm high is of white pigment colour on black background.

Anemometer

• General Description :
  
  • The wind speed is measured using anemometer. The instrument has a cup wheel consisting of three conical cups with beaded edges, free to rotate in a horizontal plane. The cup wheel spindle is connected by worm gearing to a revolution counter mounted inside a waterproof housing. The gear ratio between the cup and counter spindles is so chosen that the run of the wind is shown directly in kilometers.
  • The surface wind for synoptic purpose is reported in knots. To determine the wind speed at the time of observation, take two successive readings of the anemometer at an interval of three minutes. Subtract the first reading from the second one and multiply the difference by 20. This gives the mean wind speed over a period of three minutes in kilometers per hour. To obtain the mean windspeed in knots multiply this by 0.54.

Specifications :

• Material :
  
  • Cups - Copper or aluminium sheets 0.71 mm thickness
  • Centre spindle - Stainless steel rod
  • Worm on center spindle - Cut from manganese bronze alloy
  • Worm wheel - Hard brass

Dimension : The general arrangement and dimensions of the cup counter anemometer shall be as shown in fig. 7.1.

Counter : Any suitable non reset direct-drive revolution counter adding one count for each one-tenth revolution of the drive shaft in one direction or ten units for each complete revolution shall be used.

Accuracy : When tested in a wind tunnel, the speeds calculated from the readings of the anemometer counter shall agree with the true speeds within tolerances specified below -

• Speed - Tolerance
• Below 10 km/h - 1 kmph
• Above 10 km/h - 10%

General Description : Thermometer screens are used for mounting the various meteorological thermometers. A screen should be, as far as possible, be designed to provide an enclosure with a uniform temperature the same as that of outside air. It should completely surround the thermometers and should exclude radiant heat and precipitation. The walls of such a screen should preferably be double-louvered and the floor should be made of staggered boards, but other types of construction may be found to meet the above requirements. The roof should be double-layered, with provision for ventilation of the space between the two layers.

Specifications : Two types of thermometer screens are available.

• Small for the four meteorological thermometers
• Large —for thermograph and hygrograph

Dimensions :

• Small screen
  • Length (Betweeninner slots of louvers)- 560 mm
  • Breadth (Between inner slots of louvers) - 315 mm
  • Height (Between middle of lower roof and floor)- 412 mm

• Large screen
  • Length (Betweeninner slots of louvers)- 1325 mm
  • Breadth (Between inner slots of louvers) - 315 mm
  • Height (Between middle of lower roof and floor)- 412 mm

All dimensions within ±5%. The screen should be constructed with seasoned teak or deodar wood and painted with non-hygroscopic zinc oxide paint. Refer figs. 4.1 and 4.2.

A Wind vane is used for indicating the direction from which the wind is blowing. A Wind vane consists of a horizontal Arm carrying a rectangular flat fin mounted by means of thrust rod and brass bushes in a support. The horizontal arm is balanced about its axis of rotation by counter weight attached to the end opposite to the fin. The vane and eight direction rods are supported on a suitable galvanized iron pipe threaded into a base. Casting Four direction arms carry the letter N, E, S & W which point towards the corresponding true direction while four direction rods indicate the intermediate directions. The position of the counter weight with respect to the eight direction arms indicate the wind direction and may easily be determined by interpolation to the nearest sixteen points of the compass.

Details :

• The aluminum material is used for the fabrication of the instrument so it may withstand permanent exposure in the open and has a long life. The fin is securely fixed to the horizontal arm at one end and on the other end of the arm counter weight is fixed in such a way that the complete assembly is accurately balanced about the spindle. The horizontal arm is perfectly straight and the top end of the spindle projecting up from the horizontal arm is held firmly by a nut. The bearing housing cap is locked to the spindle by a steel pin. The spindle is a straight rod turned and finished accurately such that it revolves in the bearings with the minimum friction. The spindle is locked to the bearing by means of a steel pin. The mounting ring for direction arms is made of aluminum metal and carry the eight cardinal and inter-cardinal direction arms. It is fixed to the top of the main support tube by screws.
• The mounting ring has rest level over a collar at the top of the main support is a straight galvanized steel pipe with standard pipe threads at one end for screwing into the base. The other end takes the collar and mounting ring for direction arms. The main support tube is locked to the base by a suitable steel pin. The base is cast from aluminum material and has three holes for taking the foundation bolts.
• The external surface is suitably protected with primer and finishing paint. The four directions letters N, E, S and W is painted with red colour. The complete instrument is packed by dismantled the fin from the horizontal arm and the direction rods from the mounting ring in a strong wooden case to withstand all possible transit risks.

General Description :

Surface wind is best measured by a wind vane and anemometer. Wind direction should be reported to the nearest ten degrees. Wind direction is defined as the direction from which the wind blows and is measured clockwise from geographical north. The windvane consists of a metal sheet of rectangular form fastened to a metal rod, pivoted and capable of rotating around a vertical axis with a minimum of friction. The weight of the metal sheet is balanced by a metal counter weight at the other end of the rod.

For the purpose of obtaining a satisfactory measurement, a windvane will be suitable if it is well balanced so as not to have a preferred position in case the axis is not vertical and if it is sufficiently well designed to have single equilibrium position with respect to each wind direction.

Dimensions : The general arrangment and main dimensions of windvane shall be as shown in figs. 6.1. and 6.2.

Accuracy : When the complete instrument on final assembly is held firm at bottom and the balance weight imparted an impact by a hammer weighing 0.72 Kg and having a handle length of 240 mm, it shall make not less than five and not more than ten complete revolutions.

Thermometers

• General description :
  
  • For routine observations of air temperature, including maximum, minimum, wet-bulb and soil temperatures, liquid-in-glass thermometers are commonly used. Such thermometers make use of the differential expansion of a pure liquid with respect to its glass container to indicate the temperature. The stem is a tube having a fine bore attached to the main bulb:
  • The volume of liquid in the thermometer is such that the bulb is filled completely but the stem is only partially filled at all temperatures to be measured. The changes in volume of the liquid with respect to its container are indicated by changes in the length of liquid in the stem; by calibration with respect to a standard thermometer, a scale of temperature can be marked on the stem, or on a separate scale tightly attached to the stem.

Specifications : The thermometers shall be of liquid-in-glass, solid-stem type with enamel back as follows :

• Maximum thermometer - Mercury-in-glass, having a range from 35^oc to 55^oc
• Minimum thermometer - Alcohol-in-glass, having a range from -40^oc to +50^oc
• Ordinary thermometers (wet and dry bulb) - Mercury-in-glass, having from -35^oc to +55^oc

• Soil thermometers -
  
  • iMercury-in-glass having a range from +20^oc to +65^oc at depth of 5, 10 and 20 cm.
  • from -20^oc to +50^oc at depths of 50 and 100 cm.

The graduation intervals for all the thermometers should be 0.5^oc. The accuracy of ordinary thermometers, maximum thermometers and soil thermometers should be +0.2^oC and for minimum thermometers it sh ould be 0.3^oc

The thermometers should be suitably mounted as per drawings given in IS:5681 1983. Each mounted thermometer with mount may be supplied in a wooden case with a hinged lid, of outer dimensions 400 x 110 x 65 mm. The thermometer with its mount shall be fixed to the box with two brass screws.

Sunshine recorder consists of a glass sphere mounted concentrically in a section of spherical bowl, the diameter of which is such that when the instrument is exposed to the sun's rays, they are focused sharply on a card held in grooves in the bowl. Three overlapping pairs of grooves are provided in the bowl cards suitable for different seasons of the year. The sharply focused sun's rays burn a trace on the card which has a time scale printed on it. The length of the burn indicates the period of bright sunshine during the day.

Specifications :

• Material 
  • Base - Good quality marble or similar stone, black or white
  • Sphere - Uniform and well annealed glass
  • Bowl - Tin bronze
  • Pivot - Brass 9.2.2 Dimensions  The instrument shall have the dimensions indicated in figures 9.1 and 9.2.

Sunshine cards  Properties and dimensions of sunshine cards are given in Appendix A of IS - 7243-1974.

The Sunshine Recorder is used for the accurate measurement of the duration of bright sunshine at a place. The Sunshine Recorder consists of a glass sphere mounted concentrically in a section of a spherical bowl. Three overlapping grooves are provided in the bowl to take cards suitable for different seasons of the year. The instruments is mounted on heavy base, The scale of degree of latitude from -5 to 45 Degree. The sphere support with the glass sphere and bowl can be tilted, adjusted and clamped at an angle to suit the latitude of the station. The focused Sun's rays burn a trace on the card to indicate the period of bright sunshine during the day.

Details :

• The glass sphere has a focal length of 74.9 mm and having deviatin of e/- 0.25 mm. The base of the instruments is good quality marble stone,
• The card used in the instrument is made from white pasteboard and has a thickness in between 0.43 mm to 0.48 mm. There are three types of cards used in the instrument, namely Straight, Curved Short and Curved Long. The upper surface of the card is colored to a standard shade of the blue / dark gray colour. TtO instruments is supplied with one year cards.

Sunshine :

• Sunshine is measured using a Campbell Stokes sunshine recorder.
• Sunshine is measured in Hours per day.
• Lines on a weather map showing areas of equal sunshine are called Isohels.

Campbell-Stokes sunshine recorder :

• The glass sphere concentrates the rays of the sun and focuses them onto a strip of paper
• The paper is marked off in hourly intervals
• As the sun travels across the sky the rays are pointed towards a different section of the card
• When the sun shines it burns a mark on the paper
• The lengths of the burnt strips are added up to give the total amount of sunshine. In this case the sun shone for 7 hours.

General Description : Sunshine recorder consists of a glass sphere mounted concentrically in a section of spherical bowl, the diameter of which is such that when the instrument is exposed to the sun's rays, they are focused sharply on a card held in grooves in the bowl. Three overlapping pairs of grooves are provided in the bowl cards suitable for different seasons of the year. The sharply focused sun's rays burn a trace on the card which has a time scale printed on it. The length of the burn indicates the period of bright sunshine during the day.

Specifications :

• Material
  
  • Base - Good quality marble or similar stone, black or white
  • Sphere - Uniform and well annealed glass
  • Bowl - Tin bronze
  • Pivot - Brass 9.2.2
• Dimensions - The instrument shall have the dimensions indicated in figures 9.1 and 9.2.

Sunshine cards Properties and dimensions of sunshine cards are given in Appendix A of IS: 7243-1974.