PETROL INSTRUMENTS S.r.l.

Italian expertise in Positive Displacement flow measurement since 1970

Petrol Instruments S.r.l. is a 100% Italian manufacturer specialized in rotor-type Positive Displacement (PD) flow meters for the accurate measurement of liquid volumes in industrial and custody-transfer applications. The company has been active in flow measurement since 1970 and develops and manufactures its products at its facility in Aprilia, Italy. Its technology originates from a historical technical agreement with TOKICO, part of the Hitachi group, and has evolved through decades of engineering experience in demanding liquid-measurement applications.

Petrol Instruments is one of the few manufacturers worldwide able to supply double-case PD flow meters entirely in stainless steel, as well as versions in which the complete metering mechanism is manufactured in stainless steel. Almost all PD flow meter components are produced internally at the Aprilia factory, allowing direct control over manufacturing quality and short response times for urgent spare parts.

Complete product range for liquid measurement and control

The Petrol Instruments production line includes a broad range of equipment for measuring, controlling and verifying liquid flow:

• Double-case PD flow meters from 1 to 16 inches, covering flow rates from a few hundred litres per hour up to 2,000 m³/h.
• Single-case PD flow meters from 1 to 4 inches, for flow rates up to 150 m³/h.
• Protection strainers from 1 to 16 inches, designed to protect PD flow meters and master meters and support reliable operation over time.
• Control valves from 2 to 4 inches for applications requiring high-precision flow-rate and batch control.
• Master meters from 1 to 16 inches for testing and calibration of other liquid flow meters, with high accuracy and repeatability.
• Tank provers with capacities from 50 to 10,000 litres for calibration and verification activities.

Performance for severe operating conditions

The PD flow meter range is engineered for challenging process conditions. Depending on the model and configuration, double-case meters and master meters can operate at pressures above 250 bar, temperatures above 250 °C and viscosities of 50,000 cP and higher. Typical accuracy is ±0.1% for master meters, ±0.15% for fiscal applications and ±0.5% for general-purpose measurement, with repeatability of ±0.02%.

The straight-through flow path and floating-rotor design create a very low pressure drop even at maximum flow. The rotors do not touch each other or the other elements forming the measuring chamber; they are synchronized by timing gears located outside the inner casing. This configuration minimizes wear and helps maintain stable measurement performance over long periods of operation.

Design features focused on reliability and maintainability

A key characteristic of the Petrol Instruments double-case construction is the removable inner housing assembly, comprising the inner casing, rotors, shafts and gears. This metering mechanism can be removed, tested or replaced without taking the complete flow meter out of the pipeline. During line flushing or start-up operations, the inner assembly can be removed while the outer housing remains flanged to the line, helping protect the metering mechanism and reducing maintenance time.
Magnetic transmission provides static sealing between wetted and dry parts, eliminating the need for a mechanical linkage through the meter body and reducing the risk of product leakage. Carbon bearings, floating rotors and the double-case concept further contribute to reduced maintenance requirements and long service life. The compact design does not require upstream or downstream straight pipe lengths, offering installation flexibility in space-constrained systems.

Materials, accessories and system integration

Construction materials are available to suit the chemical and physical characteristics of the measured liquid, from cast iron and cast steel to several stainless-steel grades up to AISI 316L. Special resin versions with Hastelloy B shafts and screws are also available for selected diluted acids. The product range can be configured with mechanical, pneumatic and electronic accessories for local or remote indication, presetting, batching and signal transmission, including pulse outputs, 4–20 mA output and HART communication. Suitable configurations can also operate without an external power supply and provide direct local volume indication.

Quality, approvals and international presence

Petrol Instruments operates under an ISO 9001:2015 certified quality system. Its products comply with relevant PED and ATEX requirements and with international standards for custody-transfer applications, including OIML R117. The company holds a wide range of approvals and certifications for legal and industrial use in international markets, including MID-related approvals in Europe and country-specific approvals in markets such as Brazil, China, Indonesia, Malaysia, Nigeria and Kazakhstan.

The Aprilia production site extends over approximately 5,500 m², with around 2,000 m² of covered facilities dedicated to manufacturing and testing. The factory includes test stations equipped with calibrated tanks for performance testing and calibration of PD flow meters. Petrol Instruments products are installed across Europe, the Middle East, Asia, Africa, the Americas and Oceania, serving oil & gas, petrochemical, chemical and other process-industry applications where accurate, repeatable and dependable liquid measurement is essential.

With more than five decades of specialization in Positive Displacement technology, Italian manufacturing and a complete portfolio of meters, calibration equipment, valves, strainers and accessories, Petrol Instruments provides flow measurement solutions designed for high accuracy, long operating life, reduced maintenance and adaptation to specific process requirements.