January 12, 1998 WHS 98-01 

TO: County Agricultural Commissioners 

SUBJECT: APPLICATION OF CLOSED SYSTEM CRITERIA 

Questions have been raised regarding how the director’s closed 

system criteria (copy attached) relates to the personal protective 

equipment (PPE) exceptions and substitutions allowed in Title 3 

California Code of Regulations when using a closed system. This 

letter should help to clarify the issue. 

Section 6738(i) allows any person handling pesticides through a 

closed system to reduce labeling required PPE in specified 

situations. This provision applies to both liquid and dry pesticides 

and is not limited to mixing and loading. It extends to use of a 

closed application system as well. There is no further clarification 

in this section about what standards a closed system must meet. 

Section 6746 requires a closed system to be used by employees 

who mix or load certain liquid pesticides. The director’s closed 

system criteria are referenced. Both State (ENF 84-64) and federal 

(FIFRA Compliance Policy Letter 12.2) policy have long allowed 

for reduction of PPE in this situation. The provisions of section 

6738(i) should be applied to this section. 

A “closed system” is defined in section 6000. The definition 

includes a reference to the director’s criteria. The current director’s 

criteria were developed to implement the requirement of 
County Agricultural Commissioners 

January 12, 1997 

Page 2 

section 6746 and therefore address only liquid pesticides. There are 

no director’s criteria applicable to dry pesticides or to the 

application of pesticides. 

The American Society of Agricultural Engineers, in cooperation 

with U.S. EPA and other organizations [including the Department 

of Pesticide Regulation (DPR)], is developing a comprehensive 

national standard for closed systems. This standard will cover both 

liquid and dry formulations of pesticides. The Worker Health and 

Safety Branch intends to recommend that DPR adopt this standard 

as the director’s criteria when it is final. Until this situation is 

resolved, we are recommending the following interim policy. 

When a liquid pesticide is being handled pursuant to either 6738(i) 

or 6746, the director’s criteria should continue to be applied. The 

absence of director’s criteria for closed systems for dry 

formulations of pesticides and for application does not preclude a 

person from taking advantage of the allowable exceptions and 

substitutions in 6738(i). The use of these exceptions and 

substitutions does not constitute use of a pesticide in conflict with 

its labeling. The definition in section 6000 should be used to 

evaluate closed systems for dry formulations but the reference to 

the director’s criteria is not applicable and should not be used in 

this case. A manufacturer’s certification that their system meets the 

Worker Protection Standard is also acceptable. DPR does not 

anticipate approving closed systems for dry formulations of 

pesticides. 
County Agricultural Commissioners 

January 12, 1997 

Page 3 

Attached is U.S. EPA’s response to questions on this issue. Their 

response is consistent with the policy outlined above. Pursuant to 

section 6701 it is accepted as DPR’s interpretation. 

Sincerely, 

[Original signed by John M. Donahue and Charles M. Andrews]

John M. Donahue, Chief Charles M. Andrews, Chief 

Worker Health and Safety Branch Pesticide Enforcement 

Branch 

(916) 445-4222 (916) 445-3920 

Attachments 

cc: Mr. Daniel J. Merkley, County Agricultural Commissioner 

Liaison (w/attachments) 
CALIFORNIA DEPARTMENT OF PESTICIDE REGULATION 

WORKER HEALTH AND SAFETY BRANCH 

1020 N STREET 

SACRAMENTO, CALIFORNIA 95814-5624 

CLOSED SYSTEMS 

Revised January 2, 1998 

Design/Performance Criteria:

To meet California's requirements, a closed system should meet the following 

criteria. These criteria do not preclude closed systems utilizing procedures other 

than those outlined. Questions concerning the ability of other procedures to meet 

the closed system requirement should be addressed to the Department of Pesticide 

Regulation (DPR). 

1. The liquid pesticide must be removed from its original shipping container and 

transferred through connecting hoses pipes, and/or couplings that are sufficiently 

tight to prevent exposure of any person to the concentrate, use dilution, or rinse 

solution. 

2. All hoses, piping, tanks, and connections used in conjunction with a closed 

system must be of a type appropriate for the pesticide being used and, the pressure 

and vacuum of the system. 

3. All sight gauges must be protected against breakage. Sight gauges must be 

equipped with valves so the pipes to the sight gauge can be shut off in case of 

breakage or leakage. 

4. The closed system must adequately measure the pesticide being used. Measuring 

devices must be accurately calibrated to the smallest unit in which the material is 

being weighed or measured. Pesticide remaining in the transfer lines may affect the 

accuracy of measurement and must be considered. 

5. The movement of a pesticide concentrate beyond a pump by positive pressure 

must not exceed 25 pounds per square inch (psi) of pressure. 

6. A probe must not be removed from a container except when: 
a. The container is emptied and the inside, as well as the probe, have been 

rinsed in accordance with item 8. 

b. DPR has evaluated the probe and determined that, by the nature of its 

construction or design, it eliminates significant risk of worker exposure to 

the pesticide when it is withdrawn from a partial container. 

c. The pesticide is used without dilution and the container has been emptied. 

7. Shut-off devices must be installed on the exit end of all hoses and at all 

disconnect points to prevent the pesticide from leaking when the transfer is stopped 

and the hose is removed or disconnected. 

a. If the hose carried pesticide concentrate and has not been rinsed in 

accordance with item 8, a dry break coupler that will minimize pesticide loss 

to not more than two milliliters per disconnect must be installed at the 

disconnect point. 

b. If the hose carried a pesticide use dilution or rinse solution, a reversing 

action pump or a similar system that will empty the hose may be used as an 

alternative to a shutoff device. 

8. When the pesticide is to be diluted for use, the closed system must provide for 

adequate rinsing of containers that have held less than 60 gallons of a liquid 

pesticide. Rinsing must be done with a medium, such as water, that contains no 

pesticide. 

a. The system must be capable of spray-rinsing the inner surfaces of the 

container and the rinse solution must go into the pesticide mix tank or 

applicator vehicle via the closed system. The system must be capable of 

rinsing the probe, if used, and all hoses, measuring devices, etc. 

b. A minimum of 15 psi of pressure must be used for rinsing. 

c. The rinsing must be continued until minimum of 10 gallons or one-half of 

the container volume, whichever is less, has been used. 

d. The rinse solution must be removed from the pesticide container 

concurrently with introduction of the rinse medium. 
e. Pesticide containers must be protected against excessive pressure during 

the container rinse operation. The maximum container pressure must not 

exceed five psi. 

9. Each commercially produced closed system or component to be used with a 

closed system must be sold with: 

a. Complete instructions consisting of a functional operating manual and a 

decal(s) covering the basic operation. The decal(s) must be placed in a 

prominent location on the system. 

b. Specific directions for cleaning and maintenance of the system on a 

scheduled basis. 

c. Information on any restrictions or limitations relating to the system, such 

as pesticides that are incompatible with materials used in the construction of 

the system, types (or sizes) of containers or closures that cannot be handled 

by the system, any limits on ability to correct or over measurement of a 

pesticide, or special procedures or limitations on the ability of the system to 

deal with partial containers. 

Operating Requirements:

10. The system must be cleaned and maintained according to the manufacturer's 

instructions. If the system is not a commercially produced system it must be 

maintained on a regular basis. A record of cleaning and maintenance must be 

maintained. 

11. All labeling required personal protective equipment (PPE) must be present at 

the work site. Protective eyewear must be worn while using a closed system that 

operates under pressure. While using a closed system, PPE requirements may be 

reduced or modified as provided in Title 3 California Code of Regulations, section 

6738. 

Information about closed systems which have been evaluated and found to meet 

these criteria is available from DPR. 
Worker Protection Questions & Answers 

4.1 Definitions Q. What is the definition of a closed system? What 

 (continued) personal protective equipment is required when a 

4.14 closed systems closed system is used? 

A. At 40 CPR part 170.240(d)(4), the WPS defines 

closed systems and allows exceptions to labeling 

required personal protective equipment (PPE) when a 

closed system is used provided certain conditions and 

requirements are met. These exceptions to PPE are 

allowed unless expressly prohibited by the product 

labeling. 

Closed systems are systems designed by the 

manufacturer to enclose the pesticide to prevent it from 

contacting handlers or other people while it is being 

handled. Such systems must function properly and be 

used and maintained in accordance with the 

manufacturer's written operating instructions. Closed 

systems manufactured by a private person which meet 

the criteria in the regulations, including the requirement 

for written instructions, are acceptable. 

Examples of closed systems include: 

1) closed mixing/loading systems; 

2) closed application systems designed to incorporate 

pesticides into soil, but only if the system does not allow 

any pesticide contact with the air throughout the entire 

application process. 

3) water soluble bags while the bag is intact. 

The WPS provides that handler employers may allow 

handlers to omit some of the PPE listed on the pesticide 

labeling for a handling task if the handlers are using a 

closed system: 

1) When using a closed system to mix or load 
Worker Protection Questions & Answers 

4.1 Definitions pesticides with the signal word "DANGER" or 

 (continued) "WARNING," handlers need not wear all the PPE listed 

 on the pesticide labeling, but must wear at least: 

4.14 closed systems 

 (continued) -long-sleeved shirt and long pants, 

-shoes and socks, 

- a chemical-resistant apron, and protective gloves 

specified on the pesticide labeling for mixing, 

loading, and other handling 

2) When using a closed system to mix or load pesticides 

with the signal word "CAUTION," handlers need not 

wear all the PPE listed on the pesticide labeling, but 

must wear at least: 

-long-sleeved shirt and long pants, and 

-shoes and socks. 

3) When using a closed system to do handling tasks 

other than mixing and loading with ANY pesticide, 

handlers need not wear all of the PPE listed on the 

pesticide labeling, but must wear at least: 

-long-sleeved shirt and long pants, and 

-shoes and socks. 

4) When using a closed system that operates under 

pressure, handlers may wear the reduced PPE specified 

above, but must add protective eyewear. 

Even when reduced PPE is permitted to be worn during 

a task, handlers must be provided all PPE required by 

the pesticide labeling for that task and have it 

immediately available for use in an emergency. 
Worker Protection Questions & Answers 

4.1 Definitions NOTE: For mixing/loading/transferring of pesticides 

 (continued) outside the scope of WPS, follow the FIFRA 

 Compliance Program Policy 12.2, Pesticides Closed 

4.14 closed systems Transfer, Mixing/Loading and Application Equipment 

 (continued) (Closed Systems). 

Worker Protection Questions & Answers 

4.1 Definitions Q. Is a water soluble bag considered a closed 

 (continued) system? 

4.15 water-soluble A. Yes, for WPS purposes, a water soluble bag is 

 bags considered a closed loading system and, unless 

prohibited by the product labeling, handlers may be 

permitted to wear reduced personal protective 

equipment (PPE) as outlined in 40 CFR part 

 170.240(d)(4). 

Once a water soluble bag is dissolved, broken, 

punctured, torn, or otherwise allows its contents to 

escape, it is no longer a closed system and labelspecified PPE must be worn. In the case of routine 

mixing and loading with water soluble bags, labelspecified PPE for the activity performed must be worn 

nce the bags have lost their integrity, i.e., begin to 

dissolve in the tank, unless the mix Tank and transfer 

system are closed systems. (February 24, 1994)