Water volume control

Table 3. Nozzle ratios

Litres of water delivered to a sector during the irrigation interval using the 1 litre probe

control nozzle

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Phone: (08) 8244 0071

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Measured Irrigation

The volume of water delivered to each sector is determined by the relationship between the irrigation nozzle for the sector and the control nozzle.

You can forget about the flow rate and you can forget about the length of the irrigation interval, both will adjust automatically. All that matters is the relationship between the irrigation nozzle and the control nozzle. It’s that simple.

Measured irrigation represents a conceptual breakthrough in the development of irrigation systems. The high cost and high maintenance for drip irrigation systems are a consequence of the erroneous assumption that an accurate and reliable irrigation system needs to be pressurised. Measured irrigation is an unpressurised system that is accurate and reliable, and less than the cost of a comparable drip irrigation system.

Before you establish your irrigation system you can decide in advance the volume of water that will be delivered during the irrigation interval to each plant in your garden, orchard or plantation. Hence you will know in advance the total volume of water that will be used during the irrigation interval.

The following two tables show the volume of water delivered to a sector by each of the 17 irrigation nozzles. In the first table the brown nozzle is the control nozzle and in the second table the yellow nozzle is the control nozzle. The control volume is the volume of water required to raise the water level in the birdbath controller from the low level to the high level. The control volume can be set to 2 litres, 1.5 litres or 1 litre by using the 2 litre probe, the 1.5 litre probe or the 1 litre probe, respectively.

Table 1. Brown control nozzle

Litres of water delivered during the irrigation interval using the
1 litre probe and a brown control nozzle.

Using any other probe, a corresponding table can be created by multiplying the volumes in Table 1 by the control volume for the particular probe.

Table 2. Yellow control nozzle

Litres of water delivered during the irrigation interval using the
1 litre probe and a yellow control nozzle.

Using any other probe, a corresponding table can be created by multiplying the volumes in Table 2 by the control volume for the particular probe.

Nozzle calibration

For any combination of irrigation nozzle and control nozzle, there is a simple method to work out the volume of water delivered by the irrigation nozzle during the irrigation interval. Over the same period of time collect the water from the irrigation nozzle in one container and the water from the control nozzle in another container. Then the volume of water delivered by the irrigation nozzle during the irrigation interval is simply the control volume multiplied by the ratio of the water volumes in the two containers.

Dot2dot hose sector

Frictional head loss is rarely a problem with measured irrigation. If a part of the Dot2dot hose is more than 5 metres away from its water supply via the polypipe, you may wish to measure the head loss along the hose by inserting a pressure monitor tube at the connection to the polypipe and at the farthest point on the Dot2dot hose. To measure the frictional head loss accurately the hose needs to be horizontal. For long lengths of Dot2dot hose, you can compensate for frictional head loss by making the end of the hose lower than the beginning so that a pressure monitor tube at the beginning of the hose shows an identical pressure to a pressure monitor tube at the end of the hose.

Dot2dot hose should not be used in pressurised systems and standard porous hose for pressurised systems should not be used with measured irrigation.

Dripper sector

The nozzle formula is used above to determine the volume of water delivered to a sector during the irrigation interval. The nozzle formula can also be used to determine the volume of water delivered by a dripper nozzle during the irrigation interval. In particular,

(the volume of water delivered by a dripper nozzle during the irrigation interval)
= (the control volume) x (the nozzle ratio)

Over time you may realise that some plants are getting too much water and other plants are not getting enough. It is easy to change the dripper nozzles accordingly and, if necessary, to change the flow splitter nozzles.

Single outlet sector

For some sectors Dot2dot hose and dripper nozzles may not be the preferred method of delivering water to the plants. For example, a large deep rooted tree may be better irrigated with a watering spike that reaches the root zone. This is a single outlet sector where all the water for the sector is delivered to the watering spike. If there is an individual plant that are much higher of much lower than all the other plants, then a single outlet sector may be appropriate for such plants.

A single outlet sector may be small tank or container that receives a fixed volume of water during the irrigation interval. Hence measured irrigation has other applications besides irrigation. For example it can be used to efficiently deliver water to drinking containers for animals. You can control the volume of water delivered to each container.

Too much on not enough water

If you decide that your plants are getting too much water during the irrigation interval, simply increase the size of the control nozzle. On the other hand, if you decide that your plants are not getting enough water during the irrigation interval, simply decrease the size of the control nozzle.

nozzle formula

The relationship between an irrigation nozzle and the control nozzle is represented by the nozzle ratio. In particular, the nozzle ratio is the ratio of the flow rate for the irrigation nozzle to the flow rate for the control nozzle when both nozzles are at the same pressure. Because the nozzles are all at the same level, the head of water for all nozzles is the same, and so all nozzles are at the same pressure. Table 3 lists the nozzle ratio for any combination of stainless steel control nozzle and stainless steel irrigation nozzle.

The nozzle ratio is used in the nozzle formula:

(the volume of water delivered to an irrigation sector during the irrigation interval)
= (the control volume) x (the nozzle ratio)

The nozzle ratio is also the number of litres of water delivered to an irrigation sector by an irrigation nozzle when the 1 litre probe is being used.

The number of litres of water delivered to a sector during the irrigation interval using any other probe is obtained by multiplying the corresponding number in the above table by the control volume for the particular probe. Below are the tables for the 1.5 litre probe and the 2 litre probe.

Table 4. Litres of water delivered to a sector during the irrigation interval using the 1.5 litre probe

control nozzle

Table 5. Litres of water delivered to a sector during the irrigation interval using the 2 litre probe

control nozzle

Measured Irrigation Video

the nozzle formula

Click here to watch

4 min 42 sec

	black	green	yellow	brown	pink	white	purple	orange	olive	4.2 rivet	5.4 rivet	6.4 rivet	8.4 rivet	washer
black	1.00	0.556	0.367	0.211	0.114	0.0741	0.0533	0.0421	0.0292	0.0163	0.0112	0.0080	0.0048	0.0031
green	1.80	1.00	0.661	0.379	0.206	0.133	0.0960	0.0758	0.0526	0.0293	0.0202	0.0145	0.0086	0.0056
yellow	2.73	1.51	1.00	0.574	0.311	0.202	0.145	0.115	0.0796	0.0443	0.0306	0.0219	0.0130	0.0085
brown	4.75	2.64	1.74	1.00	0.543	0.352	0.253	0.200	0.139	0.0772	0.0534	0.0382	0.0226	0.0148
pink	8.75	4.86	3.21	1.84	1.00	0.648	0.467	0.368	0.255	0.142	0.098	0.0704	0.0417	0.0273
white	13.5	7.50	4.95	2.84	1.54	1.00	0.720	0.568	0.394	0.220	0.152	0.109	0.0643	0.0422
purple	18.8	10.4	6.88	3.95	2.14	1.39	1.00	0.789	0.547	0.305	0.211	0.151	0.0893	0.0586
orange	23.8	13.2	8.72	5.00	2.71	1.76	1.27	1.00	0.693	0.386	0.267	0.191	0.113	0.0742
olive	34.3	19.0	12.6	7.21	3.91	2.54	1.83	1.44	1.00	0.557	0.385	0.276	0.163	0.107
4.2 rivet	61.5	34.2	22.6	12.9	7.03	4.56	3.28	2.59	1.80	1.00	0.691	0.495	0.293	0.192
5.4 rivet	89.0	49.4	32.7	18.7	10.2	6.59	4.75	3.75	2.60	1.45	1.00	0.716	0.424	0.278
6.4 rivet	124	69.0	45.6	26.2	14.2	9.20	6.63	5.23	3.63	2.02	1.40	1.00	0.592	0.388
8.4 rivet	210	117	77.1	44.2	24.0	15.6	11.2	8.84	6.13	3.41	2.36	1.69	1.00	0.656
washer	320	178	117	67.4	36.6	23.7	17.1	13.5	9.34	5.20	3.60	2.58	1.52	1.00

nozzle name	description	litres of water delivered during irrigation interval
black	stainless steel needle nozzle, 0.51mm ID	0.211
green	stainless steel needle nozzle, 0.56mm ID	0.379
blue tapered	blue plastic tapered nozzle, 0.38mm ID at tip (cut off tip for desired flow rate)	0.4 to 21 litres
yellow	stainless steel needle nozzle, 0.63mm ID	0.574
brown (control nozzle)	stainless steel needle nozzle, 0.84mm ID	1.00
pink	stainless steel needle nozzle, 0.97mm ID	1.84
white	stainless steel needle nozzle, 1.22mm ID	2.84
purple	stainless steel needle nozzle, 1.35mm ID	3.95
orange	stainless steel needle nozzle, 1.50mm ID	5.00
olive	stainless steel needle nozzle, 1.75mm ID	7.21
adjustable	black plastic adjustable nozzle	0 to 12 litres
white tapered	white tapered plastic nozzle (cut off tip for desired flow rate)	12 to 200 litres
4.2 rivet	stainless steel rivet nozzle 4.2	12.9
5.4 rivet	stainless steel rivet nozzle 5.4	18.7
6.4 rivet	stainless steel rivet nozzle 6.4	26.2
8.4 rivet	stainless steel rivet nozzle 8.4	44.2
washer	stainless steel washer nozzle, 4.76mm	67.4

nozzle name	description	litres of water delivered during irrigation interval
black	stainless steel needle nozzle, 0.51mm ID	0.367
green	stainless steel needle nozzle, 0.56mm ID	0.661
blue tapered	blue plastic tapered nozzle, 0.38mm ID at tip (cut off tip for desired flow rate)	0.7 to 36 litres
yellow (control nozzle)	stainless steel needle nozzle, 0.63mm ID	1.00
brown	stainless steel needle nozzle, 0.84mm ID	1.74
pink	stainless steel needle nozzle, 0.97mm ID	3.21
white	stainless steel needle nozzle, 1.22mm ID	4.95
purple	stainless steel needle nozzle, 1.35mm ID	6.88
orange	stainless steel needle nozzle, 1.50mm ID	8.72
olive	stainless steel needle nozzle, 1.75mm ID	12.6
adjustable	black plastic adjustable nozzle	0 to 21 litres
white tapered	white tapered plastic nozzle (cut off tip for desired flow rate)	21 to 360 litres
4.2 rivet	stainless steel rivet nozzle 4.2	22.6
5.4 rivet	stainless steel rivet nozzle 5.4	32.7
6.4 rivet	stainless steel rivet nozzle 6.4	45.6
8.4 rivet	stainless steel rivet nozzle 8.4	77.1
washer	stainless steel washer nozzle, 4.76mm	117

	black	green	yellow	brown	pink	white	purple	orange	olive	4.2 rivet	5.4 rivet	6.4 rivet	8.4 rivet	washer
black	1.50	0.833	0.550	0.316	0.171	0.111	0.0800	0.0632	0.0438	0.0244	0.0169	0.0121	0.0071	0.0047
green	2.70	1.50	0.991	0.568	0.309	0.200	0.144	0.114	0.0788	0.0439	0.0303	0.0217	0.0129	0.0084
yellow	4.09	2.27	1.50	0.861	0.467	0.303	0.218	0.172	0.119	0.0665	0.0459	0.0329	0.0195	0.0128
brown	7.13	3.96	2.61	1.50	0.814	0.528	0.380	0.300	0.208	0.116	0.0801	0.0573	0.0339	0.0223
pink	13.1	7.29	4.82	2.76	1.50	0.972	0.700	0.553	0.383	0.213	0.147	0.106	0.0625	0.0410
white	20.3	11.3	7.43	4.26	2.31	1.50	1.08	0.853	0.591	0.329	0.228	0.163	0.096	0.0633
purple	28.1	15.6	10.3	5.92	3.21	2.08	1.50	1.18	0.821	0.457	0.316	0.226	0.134	0.0879
orange	35.6	19.8	13.1	7.50	4.07	2.64	1.90	1.50	1.04	0.579	0.400	0.287	0.170	0.111
olive	51.4	28.5	18.9	10.8	5.87	3.81	2.74	2.16	1.50	0.835	0.577	0.413	0.245	0.161
4.2 rivet	92.3	51.3	33.9	19.4	10.5	6.83	4.92	3.88	2.69	1.50	1.04	0.742	0.439	0.288
5.4 rivet	134	74.2	49.0	28.1	15.3	9.89	7.12	5.62	3.90	2.17	1.50	1.07	0.636	0.417
6.4 rivet	186	104	68.4	39.2	21.3	13.8	9.94	7.85	5.44	3.03	2.09	1.50	0.888	0.582
8.4 rivet	315	175	116	66.3	36.0	23.3	16.8	13.3	9.20	5.12	3.54	2.54	1.50	0.98
washer	480	267	176	101.1	54.9	35.6	25.6	20.2	14.0	7.80	5.39	3.86	2.29	1.50

	black	green	yellow	brown	pink	white	purple	orange	olive	4.2 rivet	5.4 rivet	6.4 rivet	8.4 rivet	washer
black	2.00	1.11	0.734	0.421	0.229	0.148	0.107	0.0842	0.0584	0.0325	0.0225	0.0161	0.0095	0.0063
green	3.60	2.00	1.32	0.758	0.411	0.267	0.192	0.152	0.105	0.0585	0.0404	0.0290	0.0171	0.0113
yellow	5.45	3.03	2.00	1.15	0.623	0.404	0.291	0.229	0.159	0.0886	0.0612	0.0439	0.0260	0.0170
brown	9.50	5.28	3.49	2.00	1.09	0.704	0.507	0.400	0.277	0.154	0.107	0.0765	0.0452	0.0297
pink	17.5	9.72	6.42	3.68	2.00	1.30	0.933	0.737	0.511	0.285	0.197	0.141	0.0833	0.0547
white	27.0	15.0	9.91	5.68	3.09	2.00	1.44	1.14	0.788	0.439	0.303	0.217	0.129	0.0844
purple	37.5	20.8	13.8	7.89	4.29	2.78	2.00	1.58	1.09	0.610	0.421	0.302	0.179	0.117
orange	47.5	26.4	17.4	10.0	5.43	3.52	2.53	2.00	1.39	0.772	0.534	0.382	0.226	0.148
olive	68.5	38.1	25.1	14.4	7.83	5.07	3.65	2.88	2.00	1.11	0.770	0.551	0.326	0.214
4.2 rivet	123	68.3	45.1	25.9	14.1	9.11	6.56	5.18	3.59	2.00	1.38	0.990	0.586	0.384
5.4 rivet	178	98.9	65.3	37.5	20.3	13.2	9.49	7.49	5.20	2.89	2.00	1.43	0.848	0.556
6.4 rivet	249	138	91.2	52.3	28.4	18.4	13.3	10.5	7.26	4.04	2.79	2.00	1.18	0.777
8.4 rivet	420	233	154	88.4	48.0	31.1	22.4	17.7	12.3	6.83	4.72	3.38	2.00	1.31
washer	640	356	235	135	73.1	47.4	34.1	26.9	18.7	10.4	7.19	5.15	3.05	2.00