Section 3

Flow Proportional Constant Time, Variable Volume Sampling (CTVV)

A Level-Velocity Sensor Input must be logged and electrically connected for the CTVV feature to work correctly.

CTVV samples are taken at user-specified constant (fixed) intervals. However the actual volume of each sampling is based on the known average flow rate of the site, the actual metered flow rate for each specific interval, the total sample volume desired, the user-specified collection period, and the specified Sampling Interval. Depending on the flow volumes of a stream and various intervals within the Collection Period, the volume of individual sampling can vary. Also, the total sample collected during the entire period can carry slightly above or below the Total Volume Desired. For these reasons, the manufacturer advises to use a sampling container that has a larger volume than the Total Volume Desired value.

•Sample Distribution menus are not available when CTVV is selected.

•A level-velocity sensor input must be logged and electrically connected for the CTVV feature to correctly work.

•The Flow Pacing Mode menu within the Flow Proportional menus sequence will not remember the previous setting whenever you re-enter this menu, it will revert to the CVVT default. When re-entering this menu, press CHANGE CHOICE to select the sampling method, CVVT or CTVV.

Example:

This is an example of how the instrument determines sample volume, based on user inputs and actual metered flow volume.

The user entered values are the following:

•Average Flow Rate (historical, site specific): 150 gph

•Sampling Interval: 2 minutes

•Total Sample Volume Desired: 1500 mL

•Collection Sampling Period: 30 minutes

Calculation 1: Total Number of Samples

----Sample----------------------Period-------------------

= 30---------min.---------- = 15 samples total within specified period

Sampling Interval

2 min.

 

 

Calculation 2: Average Sample Volume

 

 

Total----------------Sample----------------------Volume----------------------Desired-------------------=

------------1500---------------mL------------------

= 100 mL/sample

Total Number of Samples

15 samples Total

 

Calculation 3: Sample’s Volume per unit of Flow Rate

 

Avg.--------------Sample----------------------Volume-------------------= 100------------mL/Sample-----------------------------= 0.7mL/gph

Avg. Flow Rate

150 gph

 

Calculation 4: Actual Sample Volume to be Collected

Sample Volumes per unit of Flow Rate ⋅ Actual metered Flow Rate

0.7 mL/gph ⋅ 150 gph = 105 mL for this sample interval

 

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8990startup.fm

Basic Programming Setup

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Hach 900 MAX manual Example, Calculation 2 Average Sample Volume
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900 MAX specifications

The Hach 900 MAX is an advanced analytical instrument designed to perform water quality analysis with precision and efficiency. This multiparameter water quality analyzer is tailored for a wide range of applications, including environmental monitoring, wastewater treatment, and industrial processes. Its unique design and technology make it a valuable tool for professionals in the field.

One of the standout features of the Hach 900 MAX is its ability to measure multiple parameters simultaneously. Equipped with advanced sensors, the device can analyze key water quality indicators such as pH, turbidity, dissolved oxygen, conductivity, and various chemical parameters. This comprehensive measurement capability allows users to gain a complete understanding of water quality in a single run, saving both time and resources.

The Hach 900 MAX utilizes cutting-edge technologies to provide accurate and reliable results. Its integrated optical sensors employ advanced photometry, which enhances the detection of chemicals in water samples with high sensitivity. Additionally, the device includes advanced calibration management tools that ensure consistent accuracy over time. Users can easily perform routine calibrations with minimal effort, facilitating reliable data collection.

Another notable characteristic of the Hach 900 MAX is its user-friendly interface. The instrument features a large, touchscreen display that allows for intuitive navigation through various settings and parameters. Users can quickly access real-time data, generate reports, and analyze trends using the built-in software. The ability to customize dashboards and create visual representations of data enhances user experience and simplifies the decision-making process.

In addition to its analytical capabilities, the Hach 900 MAX emphasizes connectivity and data management. The instrument can be connected to laboratory information management systems (LIMS) and other data networks, enabling smooth data transfer and integration into existing workflows. This connectivity enhances collaboration among team members and facilitates compliance with regulatory requirements.

Durability is another hallmark of the Hach 900 MAX. The device is designed for use in demanding environments, with robust construction and protection against dust and moisture. This reliability ensures that the analyzer remains operational even in challenging conditions, making it suitable for field applications.

Overall, the Hach 900 MAX stands out as a powerful and versatile tool in the realm of water quality analysis. With its multiparameter measurement capabilities, advanced sensor technologies, user-friendly interface, and reliable performance, it enables professionals to obtain accurate insights into water quality efficiently. As environmental concerns continue to grow, instruments like the Hach 900 MAX play a crucial role in ensuring the safety and sustainability of water resources.
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