The expensive cost of flow meter for higher pipe size is a weakness of advancement of technology. Therefore, the writer uses orifice plate. In this study, the researcher uses orifice plate with a thickness of 3 mm. Orifice plate meter, this tool has more advantage than the other flowmeter, such as the construction is more simple, inexpensive in manufacture, and easy to install. This research is expected to provide an important role in fluid mechanics and can be applied in the industrial sector with the aim of providing cheaper flow meter options while still producing high precision values. The second, the researcher uses PVC pipes with ½ inch and 1 inch. The researcher uses it because both of pipes are easy to find in the market and for the costs, it is relatively cheap. The last the researcher uses Manometer U, it is used to get a high pressure difference value. Moreover, this study aims to determine the orifice debit in ½ inch and 1 inch pipes which have a value of beta (β) = 0,24 ratio and compare with the actual debit. The simmilar beta ratio value is expected to be used to predict debit in 1 inch pipe. Data retrieval method is carried out by varying the readable debit on the rotameter from 1,5 to 9 LPM and recorded in every the rising of 0,5 LPM. The pressure difference data that has been obtained is used to get the coefficient of discharge and orifice debit values. The difference between the coefficient of discharge values in the ½ inch and 1 inch pipes is the highest is 0,11 which, is given a value of 13%, while the lowest is 0,047 which, if given a value of 6%. The highest difference occurs in the Reynolds number of 1720, while the lowest difference occurs at Reynolds number 6220 to 8720. By using the assumption of ΔCd ≤ 10%, the value of Cd1/2 is considered the same as the Cd1 value which means that the orifice plate is 0,24 beta ratio in the ½ inch pipe can be used to predict on a 1 inch pipe in the range of Reynolds number 3220 to 9220.