Flushing on Pivot corners

[sditape]

We are trying to get flushing to work on a pivot corner measuring 1200' x 850', submain is on the 1200' side and the flushline is around the radius of the pivot. Longest tapes are 850' and the shortest are 30'. In the tape block entity flushing tab the flushline is split in two by checking the even flow box setting it to 2 manifolds and setting it to 1 ft/s. The tape is Typhoon 636 .18 on 24" spacing and the lateral spacing is 60". The valve is located on the end where the longest tapes are and we can get the long tapes to flush and look like reasonable numbers, but when we go to flush manifold number 2 we are getting 295gpm out of the flush manifold and we are only putting 257gpm through the valve into the submain at 16psi. Raising and lowering the pressure seems to make it more lop sided. Zone has 8.25 acres and 197 laterals and irrigates at 118.86 gpm at 12.26psi. We would be more than happy to send a design for you to look at.

[jovivier]

We would need to see the design in order to determine what is occuring in this case. Note it is the weekend here and will be Monday before we can look at it. Our email address is Support@IRRICAD.com
Alterntiavely contact NIC support.

[seng]

I look forward to your reply on this query--working on pivot corner fields in flushing mode is a challenge. Any general tips will be appreciated. Error message is that iteration number (100, and then 200) is exceeded with a shorter section. I divided the field similarly as described (3 flush manifolds, and the longest ones worked okay, but iteration error comes with Manifold 2. Thanks.

[Dan Crosby]

Hi Seng,

Again, we would need to see this design in order to analyse any problems. As per Jo's reply, you can email it to us, or contact NIC support.

Thanks,

Dan

[jovivier]

One problem that is common is having the valve a long distance from the block and not allowing for this pipe headloss when setting the valve pressure. If you know the required minimum tape inlet pressure (the V12 flushing report will tell you this) make sure to add the headloss in the pipe from the valve to the block at the higher flows.

If you receive this message:

DES_557.png

One important thing to note is that when this message appears you cannot trust the report because if the process could not finish the report may be incomplete and may be giving you half-way answers. Increase the valve pressure and re-run Detailed Analysis.

To help Detailed Analysis converge the number of iterations "Max for detailed analysis" in Design|Design Parameters|Analysis Parameters can be increased. If required the "Detailed Analysis Factor" in Design|Design Parameters|Analysis Parameters can be increased from 0.75. Likely options are 0.85, 0.9, 0.95 to a maximum 0.99.
If changing these parameters remember to set them back after you have completed the design.

In some cases Detailed Analysis cannot converge and so Analyze may need to be used.