A control valve may fit your pipe and still struggle to regulate flow at low demand. Its materials may suit the fluid at one temperature but need further review at another. Completing the control valve datasheet gives us the operating conditions needed to check these issues before proposing a valve. It also helps define the actuator, signals and accessories needed to connect the complete assembly to your plant.
You do not need to calculate Cv or choose the trim and actuator before contacting MacoTango Valve. Start with the process data and site requirements you know, and identify anything still unconfirmed. This guide explains why we request each group of inputs in our Order Form, which selection decisions they support, and how we use them to identify missing information and discuss a suitable configuration with you.
Download the order form
Use the order form for the valve and accessory request. If the size, rating or material is not yet selected, identify the missing basis in the remarks instead of guessing a value.
Order Form
Flow and pressure: can the valve control your full operating range?
Why we ask for maximum, normal and minimum flow
Maximum flow tells us how much fluid the valve must pass at peak demand. Normal and minimum flow help us assess how it will regulate during everyday operation and reduced production. A valve selected only for peak capacity may operate close to its seat at low demand, where small movements can produce a large change relative to the flow you need.
For example, a process that runs mostly at reduced load needs careful review of its low-flow operating point, even if it occasionally reaches maximum output. Providing all three flow rates helps MacoTango assess the required capacity and expected operating positions before proposing a valve size and trim.
Include the flow unit. For gas flow stated in Nm³/h, also identify the reference temperature and pressure used for that volume. If minimum flow is unknown, mark it as unconfirmed rather than entering zero unless zero flow is an actual operating requirement.
Why each flow rate needs its corresponding pressures
The pressure difference across the valve helps drive flow through it. The same valve opening can therefore pass different amounts of fluid as upstream and downstream pressures change. Pump discharge pressure alone does not establish this difference: piping and other equipment between the pump and valve also consume pressure.
Provide upstream pressure (P1) and downstream pressure (P2) at the valve for each operating case. Our Order Form has one pressure row alongside three flow entries. If pressures vary between minimum, normal and maximum flow, add the corresponding values in Remarks or an attached operating-case table. If the same pressures apply throughout, state that clearly. Identify whether pressures are gauge or absolute.
These paired conditions let us check capacity across the stated range and identify cases needing further assessment for cavitation, choked flow or noise. For more detail on the calculation process, see our control valve sizing guide.
Fluid and temperature: what could wear, corrode or block the valve?
Identify the fluid and its operating temperature
The medium name tells us what will contact the valve, but its composition and temperature can change the selection. For a chemical solution, include its concentration and any known contaminants. For a process with changing temperatures, state the normal operating temperature and relevant extremes, including cleaning conditions if the valve is exposed to them.
These details help us review the body, trim and sealing materials against the actual exposure. They also support the flow calculation: liquid density affects the capacity required for a given flow and pressure difference. If you provide specific gravity (SG), identify the temperature it represents, especially when your available value comes from a room-temperature data sheet.
Explain viscosity and suspended solids
A viscous liquid may require a correction to the sizing calculation because its flow behavior differs from that assumed in a basic turbulent-flow calculation. Provide viscosity at the operating temperature where available; a value measured under different conditions may not represent the fluid passing through the valve.
If solids are present, describe their approximate size, concentration and nature—for example, hard particles or fibers. Particles can wear throttling surfaces or lodge in narrow passages, while fibers may accumulate and obstruct flow. This information helps us assess whether a proposed trim arrangement suits the medium. Simply marking “solids present” leaves those questions unresolved.
State required materials and leave open choices for review
If your project specifies body or trim materials, enter those requirements. Otherwise, you can write “Supplier to recommend” and provide the fluid details above. A stainless steel body alone does not establish compatibility: the trim, seat, packing and gaskets also need review.
Likewise, hardfacing may help resist wear in suitable service, but it does not resolve every corrosion problem. Tell us about any previous erosion, corrosion or blockage so we can consider that failure mechanism when discussing materials and flow passages.
Size, rating and connections: will the proposed valve fit your piping?
Separate pipe size from the required valve size
Enter the line size and identify whether your project requires the valve to have the same nominal size. Pipe diameter alone does not determine the flow capacity needed for control. Depending on the operating conditions, a suitable selection may involve reduced-capacity trim or a smaller valve body with piping transitions that need review.
If you are replacing a valve, include its nameplate details and any available drawing. Tell us which dimensions must remain fixed. This lets us consider the installation constraints alongside the flow calculation before proposing a configuration.
Keep pressure rating separate from operating pressure
The pressure rating field describes a requirement for the valve’s pressure-containing construction. P1 and P2 describe the process conditions used for sizing. Both matter: a valve may provide enough flow capacity but still be unsuitable for the specified pressure and temperature envelope.
State the required rating designation, such as PN or ASME Class, together with the applicable project specification. These designations are not interchangeable pressure units, and the allowable pressure depends on the material and temperature. Add the design pressure and design temperature in Remarks or attach the piping specification if those requirements are not captured elsewhere in the form.
Describe the connection beyond “flanged” or “welded”
For a flanged valve, provide the flange standard, size, rating and facing required by the mating pipework. For a welded connection, include the required end details and pipe dimensions. A shared nominal size does not establish that two connections will fit together.
For replacements, also provide the face-to-face dimension and any limits on actuator height or maintenance access. These details help MacoTango identify installation differences early and make clear whether the proposed valve fits the existing arrangement or requires piping changes.
Valve action and utilities: what must happen when a supply fails?
Define the required response to each failure
The Valve Action field asks what the valve should do when a specified failure occurs: open, close or remain in position. The required response depends on your process. Closing may stop an unwanted feed, while opening may be necessary to maintain cooling. Your process requirements determine the intended position.
Loss of instrument air, electrical power and control signal can produce different responses. State the failure event alongside the required action, and use Remarks if the requirements differ. For example, “close on loss of air” does not fully define what should happen if the control signal disappears while air remains available. This distinction helps us review the actuator and accessory arrangement against the behavior you need.
Provide the supply available at the valve
For pneumatic actuation, provide the available instrument-air pressure, including the minimum expected during operation. Actuator force or torque depends on that supply. A nominal compressor pressure may not represent the pressure reaching the actuator when other equipment is drawing air.
Also identify the maximum differential pressure against which the valve must close or remain shut. This may differ from the differential during normal flow; enter it in Remarks if necessary. Together, the available supply and shutoff condition help us assess whether the actuator can provide the required force or torque.
For electrically powered equipment, state the available voltage and whether the supply is AC or DC, including phase and frequency where applicable. A required movement after power loss needs a suitable stored-energy or backup arrangement; selecting “fail close” on the form alone does not establish that capability.
Include the surrounding temperature
Ambient temperature describes the environment around the actuator and accessories, separately from the fluid temperature inside the valve. Provide the expected range and mention nearby heat sources or unusually cold conditions. These inputs help us review equipment limits and identify protection requirements before defining the complete package.
Positioner and accessories: what should the complete package include?
Separate the control command from position feedback
The positioner uses the control command and measured valve position to adjust the actuator toward the requested position. Tell us which command signal your control system provides. If the Order Form’s positioner options do not fully describe that interface, add the signal details in Remarks or attach your instrument specification.
Position feedback serves a separate purpose: it tells your control system where the valve is. Specify whether you need continuous position feedback, open/closed status switches, or both, together with the required signal or contact details. A positioner’s internal position measurement does not automatically mean that a separate feedback output is included.
HART adds communication functions for compatible equipment and systems. Selecting it does not, by itself, define a separate position-feedback output or ensure that your site can use its diagnostic functions. State your communication requirements and any approved brand or model restrictions so we can review the interfaces together.
Choose accessories for the functions you need
The accessory fields help define what arrives with the valve and what the site must provide. Each option has a different purpose:
- Handwheel: provides a means of manual operation through a suitable arrangement. Explain when it will be used so we can review how manual operation interacts with automatic control and the required failure response.
- Air filter regulator: filters the air supply and regulates its pressure locally. Identify any existing site provision and instrument-air requirements; this accessory alone does not resolve every air-quality issue.
- Solenoid valve: switches pneumatic paths for a defined operating or trip function. Specify its purpose, available electrical supply and required de-energized response so the pneumatic arrangement can be reviewed.
Use Other Accessories for additional requirements, such as position switches or a specified connection to the plant air system. Describing the required function helps MacoTango propose the relevant components and identify what is included, optional or supplied by others. This gives you a clearer basis for comparing complete valve quotations.
Area requirements and remarks: what else could change the selection?
Provide the hazardous-area specification
If the valve assembly will operate in a hazardous area, marking “Yes” in the explosion-proof requirement field alerts us to a constraint, but it does not provide enough information to select the associated instruments and electrical equipment. Attach the project’s area-classification and approval requirements, including the applicable gas or dust classification, temperature restrictions and protection requirements.
These requirements help us check whether the proposed positioner, solenoid and other relevant components are suitable for the installation. An approval for one component does not establish suitability for the complete assembly. If the classification is not yet available, mark it as unconfirmed so this part of the selection remains open.
Use Remarks for conditions the standard fields cannot capture
Include operating conditions that differ materially from normal production, such as startup, cleaning or reverse flow. Describe what changes and provide the corresponding fluid, temperature, flow and pressure data where known. A valve selected only around normal operation may need a different configuration when these additional duties are considered.
For a replacement, note existing problems such as leakage, noise, blockage or slow response, and when they occur. Attach relevant drawings or operating records if available. This gives us a specific issue to investigate when reviewing the replacement; copying the existing valve specification may carry the same unresolved problem into the new installation.
Also identify required inspection records, material documents, testing or other project acceptance conditions before quotation. Providing these requirements early helps MacoTango clarify the proposed supply scope and highlight deviations for your review. Use “TBD” for missing process information rather than entering an assumed value that could be mistaken for confirmed design data.
What MacoTango can check from your completed form
Your completed Order Form gives us a basis for reviewing the valve against your operating conditions and installation requirements. The first step is to identify missing or conflicting information that could change the selection. For example, flow values without corresponding pressures leave the required capacity uncertain, while a specified failure action without a defined failure event leaves the actuator arrangement open.
With sufficient information, MacoTango can assess the required flow capacity and operating range, discuss suitable valve construction and materials, and review actuator and accessory requirements. We can also identify differences between the proposed configuration and your stated requirements, so you can resolve them before approving the selection.
This review helps define what you are comparing in a quotation: the valve and actuator configuration, included accessories, required interfaces and any outstanding assumptions. Final selection remains subject to confirmed operating data and agreement on the supply scope.
Send what you know and identify what needs review
You do not need to select every component before sending an inquiry. Enter confirmed process and site information, mark unknown values as “TBD,” and use “Supplier to recommend” for equipment choices you want us to assess. If a project specification already defines a requirement, attach it rather than trying to fit every detail into a short form field.
Download the MacoTango Order Form, then submit it with your project requirements and supporting files. Include the operating problem you need the valve to solve. That context helps us focus the review on the conditions and decisions that matter to your application.