# partID volPr vs flowPr

**URL:** <https://odm.discourse.group/t/partid-volpr-vs-flowpr/113>\
**Category:** Support\
**Tags:** odm-v2-rc2\
**Created:** [March 22, 2023, 11:29am UTC](https://odm.discourse.group/t/partid-volpr-vs-flowpr/113 "2023-03-22T11:29:15Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![wastewater\_belgium](https://avatars.discourse-cdn.com/v4/letter/w/c0e974/32.png) [@wastewater\_belgium](https://odm.discourse.group/u/wastewater_belgium)\
**Post date:** [March 22, 2023, 11:29am UTC](https://odm.discourse.group/t/partid-volpr-vs-flowpr/113/1 "2023-03-22T11:29:15Z")

</div>

Hi,

What is the difference between flow proportional sampling and volume proportional by an autosampler?

---

<div class="post-metadata">

**Author:** ![matthomson](https://avatars.discourse-cdn.com/v4/letter/m/dec6dc/32.png) [@matthomson](https://odm.discourse.group/u/matthomson)\
**Post date:** [April 21, 2023, 9:24pm UTC](https://odm.discourse.group/t/partid-volpr-vs-flowpr/113/2 "2023-04-21T21:24:15Z")

</div>

Hi @wastewater_belgium ! Great question. As far as I understand it:

**24-h flow proportional composite:** The sampling is performed at constant time intervals. The volume of wastewater taken is proportional to the flow rate flowing at each instant of sampling. This is also called constant time, variable volume (CTVV).

**24-h volume proportional composite:** The sampling takes the same wastewater volume at variable time intervals, after a defined volume of wastewater has passed the sampling point.  
This is also called constant volume, variable time (CVVT).

I’m not an engineer by trade, but my information for this answer is sourced from this paper (link: [Water | Free Full-Text | Occurrence of Micropollutants in Wastewater and Evaluation of Their Removal Efficiency in Treatment Trains: The Influence of the Adopted Sampling Mode](https://www.mdpi.com/2073-4441/11/6/1152)) which goes into deeper detail of the merits of these different sampling strategies as well.

---

<div class="post-metadata">

**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/odm/original/1X/34f6410d4262a308493f8c3b977a49666a3a2929.png) [@system](https://odm.discourse.group/u/system)\
**Post date:** [April 24, 2023, 5:02pm UTC](https://odm.discourse.group/t/partid-volpr-vs-flowpr/113/3 "2023-04-24T17:02:41Z")

</div>

This topic was automatically closed 24 hours after the last reply. New replies are no longer allowed.