Frequently Asked Questions

What is the best orientation for mounting the flow meter?

For most situations, the meter can be mounted in any orientation. The special cases are:

1. High temperature where you should mount the meter so that the transmitter is to the side or below the meter. Transmitters with heat dissipating fins should be mounted sideways so that air can rise up between the fins. For other high temperature applications, mounting the transmitter underneath the meter will reduce the amount of heat which migrates into the transmitter housing.
2. If there is possibly entrained bubbles in the fluid or system it is best to place the meter on its side with fluid flowing up through the meter, or upside down so that bubbles do not collect in the measuring chambers.

Do I need flow straighteners?

Positive displacement meters are not affected by turbulence in the flow stream. It is permissible to install the meter near pumps, valves or plumbing changes. The displacement per revolution, of the meter will not change. No upstream or downstream straight runs are required.

What size filter do I need before the flow meter?

Our recommended filtration for the Piston series is 10 micron, for the Gear series it is 15 and 30 micron and for the helical rotor series the recommendation is 150 micron (100 mesh). For high viscosity fluids, you may have to loosen this specification to maintain an acceptable pressure drop in your system. Please consider the tight tolerances within the meter and possible sources of contamination. If dirt is present in your process, the recommended filtration level should be maintained.

How often must the Max flow meters be calibrated?

We do not require that the customer maintain a specific calibration interval. Many customers have adopted a 1 year interval as part of their Quality Management program. Others have established sampling techniques which test the meter in-place and only remove the meter when their sample data shows a drift beyond tolerance.

What is the price of a Max Machinery flow meter?

The price of a Max positive displacement flow meter will vary based on the size of pipe or line being measured. The various output options and other flow specification considerations are unique to each order. The graph below shows the general pricing.

Every Max meter comes with a NIST traceable calibration covering its entire 100:1 range.
Verifiable accuracies to better than 0.3% of reading.

For more accurate pricing based on your specific needs please request a quote

How do I use a current sinking transmitter to create 12 or 24 V pulses instead of 5 V?

Max offers a variation of the Model 295 transmitter which has a transistor output such that when triggered by the software, the signal line is connected to Common. Please refer to the installation sheet offered on the Technical Documents page to review the use of this circuit to provide pulse voltages different than the 5 V pulse normally provide.

What is the difference between “Accuracy of reading” and “Accuracy of full scale”?

These two claims are only equal at the maximum capacity of the measuring device. If a meter’s accuracy is based on a percentage of its full reading capability, the error is a fixed value. For example; an error of 0.5% of full scale, in a 100 gal/min device is +/- 0.5 gpm. This is the uncertainty all of the time, so as you move away from the full scale capability, the 0.5 gpm error becomes a much larger percentage. At 50 gpm, you are risking a 1% error. At 10 gpm you have a potential 5% error. On the other hand, if the device has an error expressed as a percentage of the actual flow, then a 0.5% error of 10 gpm is only +/-0.05 gpm; a 10 times better result.

What is meant by turndown ratio?

The turndown ratio is a measure of the meter’s working range. By dividing the upper most flow rate by the minimum, measureable flow rate you determine a value that is usually presented as 3:1, 10:1 or maybe 100:1 (pronounced one hundred to one). The larger the ratio the wider the operating range of the device. Meters that cannot hold their accuracy are often specified to work in a 3:1 range. Higher precision devices that hold their accuracy may be specified as 200:1 or 1000:1 devices. Such a large range makes it possible to use the same meter for both 10 L/min measurements and 10 ml/min.

What is dither and how does it affect the flow measurement?

Signal dither is a potential source of measurement error. Dither occurs when a meter generates an output when there is no net reportable flow. This is usually observed at low flow or zero flow conditions. If the meter misinterprets vibration or pulsing liquid motion it will over report the actual flow rate. To prevent this error, the flow meter must detect flow direction and buffer or ignore the change in flow. Common techniques are to use a quadrature output which will produce an alternating A pulse then B pulse. If the meter starts to dither, this output will reverse the pulse phase or possibly create a sting of “A” pulses. Special electronic displays that accept two pulse inputs can ignore the erroneous signals. For simplicity, Max transmitters use a sophisticated sensing system that tracks the meter’s position and detects the dither before producing its frequency output.

Why can’t you run water through any meter (with the exception of the Model 234)?

Almost all of the Max meters have metal-on-metal contact in the flow stream. By running a non-lubricating fluid or compressed gas you run the risk of galling the mated surfaces. There is also high-carbon, stainless-steel ball bearings submerged in the flow and they are susceptible to rust if exposed to water and air. The Model 234 meter is the exception to this restriction as it has graphite-like pistons and no ball bearings in the fluid stream, so neither galling nor
rust are an issue.

How do the part numbers relate to the meter’s features and options?

For the Piston Meters: 21X-311-000
First 3 digits:                Meter size: 213, 214, 215, 216
       4^th digit:                Pressure rating: 3 or 4 for 1000 psi, 6 for 3000 psi, 5 for 7250 psi
       5^th digit:                Plumbing connection: 1 for NPT, 8 for manifold base, 9 for SAE ports
       6^th digit:                Transmitter link: 1 for 270 and 290 Series, 0 for Model 284 (obsolete) 3 for Model 286 (obsolete)
 Last 3 digits:                O-Ring material: 000 for Viton, 72x for Teflon, 71X for Neoprene
(Other variations exist; please call Max Machinery if you have a question regarding this list)
               
For the Helical rotor meters: 241-221-000
First 3 digits:                Meter size: 241, 242, 243
      4^th digit:                Materials of construction: 2 for Stainless steel, 3 for added electric heater ports
       5^th digit:                Pressure rating: 2 for 500 psi, 3 for 500 psi with liquid heat trace, 6 for 3500 psi, 7 for 3500 psi with heat tracing
      6^th digit:                Transmitter link: 1 for 270 and 290 Series transmitters, 4 for Model 289 transmitters
       Last 3 digits:                O-Ring material: 000 for Viton, 72x for Teflon
(Other variations exist; please call Max Machinery if you have a question regarding this list)
 
For the Gear meters with built-in transmitters: G015HS11NA/P11N/1
First 4 digits:              Meter size: G004, G015, G045, G105, G240
       5^th digit:              Pressure rating: H for 6000 psi
       6^th digit:              Materials of Construction: S for stainless steel
       7^th digit:              Plumbing connection: 1 for NPT, 2 for SAE
       8^th digit:              O-Ring material: 1 for Viton®, 3 for Teflon®, 5 for Perfluoro
 9^th/10^th digit:              Options: NA for not applicable, HT for heat traced
      11^th digit:              Transmitter output: P for pulse, A for analog, Q for quadrature
      12^th digit:              Electrical connection: 1 for 5 pin Turck® plug, 2 for Ex-Proof housing
      13^th digit:              Temperature rating: 1 to 90°C, 2 to 155°C
      14^th digit:              Supply Power:      A for current output transmitter running on 24 Vdc
                                                                        B for current output transmitter running on 12 Vdc 
                                                                        C for voltage output transmitter running on 24 Vdc
                                                                        D for voltage output transmitter running on 12 Vdc
                                                                        N for pulse transmitter using between 5 and 30 Vdc
                                                                        S for pulse transmitter using a current sinking output
 
For variations not listed and model numbers for transmitters please contact the factory for assistance.

Are transmitters interchangeable between meters?

It is best to think of the sensor as a combination of a meter and transmitter.  Servicing and calibrating them as a set is always the best idea.  However, if it becomes necessary to replace a transmitter in the field, it is best to confirm that you have a proper match of meter to transmitter.  There are several alternatives for the rotating piece within the meter and each family of transmitter will only respond to the proper meter type.  In addition, there are phasing and scaling changes which should be discussed with a Max technician to maintain the optimal, meter performance.

How to get an RMA (returned materials authorization)?

Call the number at the bottom of the page and speak with a Service representative, or fill out the on-line RMA form under the main menu tab
labeled “Support”

What is a MSDS and where can I get one?

The Material Safety Data Sheet is an important health and safety document which protects both your and our employees from dangerous chemical exposure.  Whenever a meter is sent to our factory, we need a copy of the MSDS for the fluid which you have run through the meter.  If you do not have these on file, you should get one from your chemical supplier or their web site.  

Do you supply annual calibration services?

Yes, we will recalibrate all of the meters we manufactured.  We can provide “as received” calibrations and repair and certification, or “as left” calibrations.

Is your lab independently certified?

We are currently working towards outside accreditation.  Until that project is finalized, please contact us for a list of certified labs who are experienced in handling Max products.

Do you have regional service centers?

No, all assembly, testing or repairs are done at our Factory in Healdsburg, CA

Does Max Machinery have a Government Cage Code?

Yes, the number is 0BCX3

Do you offer I.S. (Intrinsically Safe) transmitters?

Max Machinery has chosen to use a high level, microprocessor based encoder on its flow meters.  The current draw required for these devices prevents our current line of transmitters from being certified as I.S.  
 
Max Machinery has built its reputation on helpful, friendly service.  If you do not see the answer to your question, please contact us between 6:30 AM and 5 PM Pacific time.  We’re happy to help and your question may make it onto this list to help others.  Thanks.